Low emissions combustion apparatus and method

ABSTRACT

Clean combustion and equilibration equipment and methods are provided to progressively deliver, combust and equilibrate mixtures of fuel, oxidant and aqueous diluent in a plurality of combustion regions and in one or more equilibration regions to further progress oxidation of products of incomplete combustion, in a manner that sustains combustion while controlling temperatures and residence times sufficiently to reduce CO and NOx emissions to below 25 ppmvd, and preferably to below 3 ppmvd at 15% O 2 .

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional App. 60/590,073,filed Jul. 21, 2004 and U.S. Provisional App. 60/579,135, filed Jun. 11,2004.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to an apparatus and method of combustion thatproduces low emissions, carbon monoxide and oxides of nitrogen inparticular, and to progressing reactions to produce low intermediateproducts and byproducts.

2. Description of the Related Art

Energy conversion and chemical processing industries, seek toeconomically remove and/or produce specific chemical species. Unburnedhydrocarbons (UHCs), carbon monoxide (CO), and oxides of nitrogen (NOx)are three sets of chemical species which are commonly found in energeticfluids formed in hot chemical reactions, and more particularly, incombustion-based energy conversion industries.

Legislative authorities have periodically reduced allowable emissionlevels of these pollutants. Manufacturers of combustion-based power andother energy-conversion systems thus seek improved pollutant reductionsystems. Methods of reducing the emissions of these and other commonpollutants typically include,

(1) modifying the combustion process itself, e.g., tuning or configuringthe combustor/burner section of the system, or adding reactants toreduce the emissions (such as ammonia), and

(2) utilizing add-on technologies that effectively reduce or removepollutant species produced in earlier phases of the overall chemical orenergy-conversion process.

In typical combustion systems, control measures aimed at controllingeach of NOx, CO and UHCs can be counterproductive, thus increasing thecost and complexity of controlling overall emissions. For example, NOxemissions are understood to increase with, (1) increasing combustiontemperatures, becoming especially important above about 1300°-1500° C.,(2) with increasing residence time at the NOx-producing temperatures,and (3) with increasing concentrations of the effective oxidant,typically O₂, at the NOx-producing temperatures. Consequently, some ofthe most common in-situ or “in-combustor” strategies for reducing NOxlevels are informed by these understanding. They sometimes involveadding a diluent, such as excess air, exhaust gas, steam or water, toreduce undesirably high temperatures in the combustor. Furthermore, themore upstream the diluent is delivered to the combustor, the shorter theresidence time at NOx-producing temperatures. In some technologiesdiluent air and/or steam is premixed with the fuel and/or oxidantcontaining fluid to constrain the peak reaction or combustion flametemperatures. To reduce the amount of oxidant available that wouldoxidize nitrogen-containing compounds to form NOx, diluents other thanair, oxygen or similar oxidants are used.

It is commonly expected that CO and UHC emissions increase withdecreasing overall combustor temperatures and reduced residence times attemperatures high enough to promote UHC and CO oxidation to CO₂.Consequently, diluent-based NOx reduction strategies typically result insimultaneous undesired increases in the CO and UHC emissions in theenergetic or working fluid leaving the combustor, and vice versa.Furthermore while higher temperatures seem to promote UHC removal, COemissions tend to increase with incremental increases in temperature inhigh temperature ranges. This is especially a problem as higher turbineinlet temperatures are sought for higher efficiency in gas turbinesystems. The CO levels produced from systems with high combustorexit/Turbine Inlet temperatures are often substantially higher thanlegislatively allowed or desired emission levels.

Efforts to increase system throughput typically result in shorter hotresidence times, further raising UHC and CO concentrations. Rapidexpansion through a work engine or expander such as a turbine typicallyresults in rapid reductions in fluid temperature that “freeze” or“quench” the conversion of UHC and CO to CO₂, which can result in highUHC and CO emissions.

As in-situ methods typically have limited success in reducing emissions,they are often combined with add-on technologies that reduce or removepollutant species produced and present in the combustion product gases,e.g. selective catalytic reduction (SCR). Such add-on techniquestypically process the exhaust gases at low pressures. The utilizedadd-on technologies often substantially increase the volume, footprintand cost of the systems because of the high specific volume andcomparatively long kinetic time-scales of reactions that characterizeexhaust gases. Thus, even though these methods may successfully reduceemissions to acceptable levels, they often substantially increaseequipment, operation and maintenance costs.

SUMMARY OF THE INVENTION

One object of the present invention is configure and control thecombustion of a carbonaceous fuel using significant levels of aqueousdiluent to control combustion temperatures and the consequent productionof NOx, at the same time maintaining stable combustion through thestaged, progressive addition of air, fuel, and diluent to the hotcombustion gases.

Another object is to control the production of partial products ofcombustion such as CO, by the use of one or more equilibration stages,wherein the temperatures and residence times are controlled to promotethe conversion of CO to CO₂.

More generally, the objects of this invention are the minimization of byproduct species and partial reaction species, in a chemical reaction,using the steps of progressive, diluted primary reaction, followed bycontrol within equilibration stages. The combustion-based embodiments ofthe present invention exemplify methods of fluid delivery to the primarycombustion region and preferentially include equilibration regions orpassages.

The strategy of Progressive Combustion is employed within the primarycombustion region—to constrain combustion below temperatures that arenormally achieved in conventional combustion systems. Progressivecombustion is able to support stable combustion of common hydrocarbonfuels at average temperatures in the primary combustion region as low as650° C., well below the lower temperature limit of significant NOxformation of about 1300° C. Gases leaving the primary combustion regionof a combustor may have higher than acceptable UHCs and/or COconcentrations. Consequently, after primary combustion is accomplished,final burnout is achieved in equilibration regions where temperature ortemperature profiles are established that support rapid removal of UHCsand/or CO, decreasing their concentrations to levels not achievable inconventional combustion regions. These equilibration region controls maybe applied after progressive combustion, or after other primarycombustion techniques, whether conventional or novel.

The main design elements of Progressive Combustion include (1)streamwise distribution of fluid delivery and (2) improved mixing orpremixing. When applied to an exempliary combustor configuration, theProgressive Combustion principle results in (1) improved stability, (2)improved peak temperature control, (3) and improved chemistry/kineticcontrol and emission reduction, when compared with conventionaltechnologies. The methods may enable mixtures, conventionally consideredas non-flammable, to be burned in a controlled and stable fashionwithout blowout.

As energetic combusting fluid flows through the combustion chamber,mixtures of oxidant, fuel and diluent fluids are delivered to thecombustion chamber so that the delivered fluids interact with the hotcombusting fluid at a plurality of locations along the streamwisedimension of the combustor. The progressive combustion sequence isinitiated by energetic pilot fluids at the upstream end of thecombustion chamber, the outflow of the pilot being the inflow of thefirst combustion stage. At each stage, prescribed quantities ofuncombusted of oxidant, fuel and diluent fluid mixtures are delivered tothe combustion chamber, mixed together, and energized by heat from theoutflow of the previous combustion stage to temperatures that supporttheir ignition and the release of their chemical energies of combustion.The energetic fluids produced by this combustion form the outflow of thecurrent stage and the inflow of the next. In the design limit, thedistribution of delivery locations may be treated as a continuousdistribution rather than discrete locations.

Progressive Combustion generally applies to the upstream primarycombustion region, where most or a significant fraction of the totalfuel, air and/or water used is delivered to the combustion chamber, orwhere most or a significant fraction of the overall exothermic releaseof chemical energies occurs. Further downstream, equilibration regionsmay be used to further lower UHC and CO concentrations to target levels.In the equilibration regions, the thermodynamic equilibrium relationshipbetween CO, CO₂ and O₂, characterized by lower CO equilibrium levels atlower temperatures, is exploited. Consequently, after excess levels ofCO and UHC are oxidized to CO₂ in the primary combustion regions, thetemperature of the energetic fluid is controlled in one or more of theprovided equilibration regions. The fluid temperature within theequilibration region is controlled to be low enough to encourage COconcentrations in the hot combustion fluids to approach the lowerequilibrium levels, while being high enough to support high enoughreaction rates to the equilibrium level.

Accordingly, in the current invention, equilibration region(s) arepreferably provided or configured downstream of the primary combustionregion(s) to reduce the high CO emissions common in power systems. Theseequilibration regions (1) establish one or more desired equilibrationtemperatures, temperature ranges or temperature paths, and (2) provideone or more corresponding equilibration residence times sufficient toreduce the CO concentration to desired levels at the end of theequilibration residence times.

In some configurations, the fluid equilibration temperature isconfigured and/or controlled to between about 850° C. and 1450° C., andmore preferably between about 1050° C. and 1250° C. for typicalhydrocarbon-air based combustion systems, depending on the targetemissions levels. These temperatures are typically below temperaturesthat form significant NOx emissions. To achieve the same COconcentrations for different mixture conditions, users generally choosehigher equilibration temperatures as the concentration of excess oxygenin the system increases, as the carbon fraction of the fuel decreases,or as the fluid pressure in the system increases.

According to the combustion system objectives and/or design limitations,users preferably provide the equilibration temperature and appropriateequilibration residence time within the equilibration region(s) by oneor more energy transfer mechanisms. These energy transfer mechanisms mayinclude, but are not limited to:

Adding of further diluent to the combustion fluid flow;

Accelerating the combustion fluid flow;

Extracting energy from the combustion fluid flow using a turbine; and/or

Transferring heat from the combustion fluid flow by one or more ofconvection, conduction and/or radiation.

According to different energy-conversion system objectives and/or designlimitations, (e.g., the Turbine Inlet Temperature for gas turbines)users preferably add equilibration regions in sequential arrangementdownstream of progressive combustion regions. Additional emissionscontrol strategies may be incorporated into the overall system asdesired. Other chemical processes may also be conducted using similarmethods.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically depicts an exemplary generalized embodiment of acombustor utilizing progressive combustion and equilibration strategiesto achieve emissions control.

FIG. 2 schematically depicts the longitudinal cross-section of anexemplary embodiment of an experimental combustor used to demonstrateaspects of progressive combustion and equilibration.

FIG. 3 is section A-A of FIG. 2, schematically depicting a transversecross-section through the stage 1 combustion region.

FIG. 4 is section B-B of FIG. 2, schematically depicting a transversecross-section through the stage 2 combustion region.

FIG. 5 is section C-C of FIG. 2, schematically depicting a transversecross-section through the stage 3 combustion region.

FIG. 6 shows graphical results of centerline temperature, COconcentration, and NO concentration for experiments performed in theexemplary embodiment of FIG. 2-FIG. 5.

FIG. 7 graphically shows the impact of the water-to-fuel ratio of thepilot on NO concentration in the exhaust fluids of the exemplaryembodiment FIG. 2-FIG. 5.

FIG. 8 schematically illustrates the impact of various delivery rateprofiles on progressive combustion stability, indicating stable,conditionally stable, and blowout regimes

FIG. 9 depicts the time-based effects of equilibration temperature on COand NO concentration in the product gases from the combustion of atypical hydrocarbon fuel with 5% of excess air and 3.15 times more waterthan the fuel mass.

FIG. 10 shows suggested equilibration temperatures at the expectedequilibration times for quickly reducing the concentration of CO incombustion product gases to target levels.

FIG. 11 schematically depicts an embodiment of the energetic sections ofa gas-turbine system comprising equilibration regions and using turbineexpanders for temperature control.

FIG. 12 is a graph of the appropriateness of suggested embodiments basedon the design temperature of selected components comprising thecombustion system.

FIG. 13 is a generalized Campbell diagram indicating regimes of flamestability, NOx formation and CO removal based on the relativeproportions of oxidant, fuel and diluent comprising the fluid mixtureinput to a typical hydrocarbon combustion system.

FIG. 14 is a graph of the results of a 1-dimensional simulation of aprogressive combustion and equilibration strategy in which progressivecombustion is caused to occur under slightly lean conditions, followedby the delivery of additional diluent to the equilibration regions ofthe system.

FIG. 15 is a graph of the results of a 1-dimensional simulation of aprogressive combustion and equilibration strategy in which progressivecombustion is caused to occur under slightly rich conditions, followedby the delivery of additional diluent and oxidant to the equilibrationregions of the system.

FIG. 16 schematically depicts a curvilinear temperature profile througha plurality of expanders with intermediate equilibrating residenceregions compared with a desired profile.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

U.S. Pat. Nos. 3,651,641, 5,617,719, 5,743,080 and 6,289,666 to Ginterare hereby expressly incorporated by reference herein. These teachdiluted combustion methods utilizing delivery of thermal diluent (suchas water) into a combustor to cool the combustion, reducing the use ofexcess dilution air. This invention further expressly incorporates byreference herein the following US patent applications by Hagen et al.:

20050056313 Method and apparatus for mixing fluids of Mar. 17, 2005

20040244382 Distributed direct fluid contactor of Dec. 9, 2004

20040238654 Thermodynamic cycles using thermal diluent of Dec. 2, 2004and

20040219079 Trifluid reactor of Nov. 4, 2004. These applications teachfurther methods of delivering aqueous diluent with improved control overtransverse temperature profiles.

FIG. 1 is a generalized representative embodiment of a combustorapparatus utilizing the Progressive Combustion and Equilibration methodsto control emissions. The figure depicts Progressive Combustion within acombustor 1 comprising a combustion chamber 2 having a plurality ofstreamwise combustion regions in fluid communication, and having aplurality of discrete streamwise fluid delivery locations. Otherconfigurations may use continuous streamwise delivery or numerousdelivery locations providing pseudo continuous streamwise delivery.

The energetic combustor fluids F9 are characterized at the upstream endof the combustion chamber 2 by entering energetic pilot fluids F8.Downstream of the entrance of the pilot fluids F8 to the combustionchamber 2, prescribed quantities of oxidant F1, fuel F2 and diluent F3fluid mixtures are delivered to the combustor 1. After delivery,uncombusted fluids F4 comprising the oxidant F1, fuel F2 and diluent F3fluids are preferably mixed within one or more premixing regions 6,forming an uncombusted premix F7. The uncombusted premix fluid F7 ispreferably mixed with the energetic pilot fluids F8 to form an energizedcombustible mix F10. Energy available from the energetic pilot fluids F8contributes to the energizing the uncombusted premix F7, heating it totemperatures that support its ignition and the release of its chemicalenergies of combustion.

Delivering uncombusted premix fluid F7 is preferably combusted to formenergized combustible mix F10. This results in an increased mass, volumeand enthalpy flow of energetic combustor fluids F9 compared to theinitial inflow of energetic pilot fluids F8 into that combustion stage.Additional quantities of the uncombusted fluids F4 are preferablydelivered to the combustion chamber 2 in a similar manner, being addedat a plurality of locations along the streamwise dimension of thechamber 2. At each delivery location, uncombusted fluids F4 arepreferably combine and are delivered to mixing regions 6. The resultingpremix fluid F7 is then incorporated with energetic combustor fluids F9.These are at temperatures higher than that of the premix fluid F7, toform an energized combustible mix F10. The constituents of the energizedcombustible mix F10 will then be about at temperatures that supporttheir combustion. This method results in increased mass, volume andenthalpy flows of energetic combustor fluids F9 from one combustionstage into the next. In the design limit, the distribution of deliverylocations may be treated as a continuous distribution rather thandiscrete locations.

In some configurations, more than one of the stages in the ProgressiveCombustion sequence are fed by a common premixing region 7. Theproportions of the oxidant F1, fuel F2 and diluent F3 constituents beingfed to stages with a common premixing region 7 are about the same givingsimilar compositions.

In some configurations, no clear boundary 8, such as a physical wall,demarcates the premixing region 6. Consequently, there may not be adistinct separation of the premixing regions 6 from regions of highcombustion reactivity where the energetic combustor fluids F9 andenergized combustible fluids F10 are situated.

Throughout the progressive combustion sequence, the temperature,composition, and streamwise delivery profile of the fluids forming thepremix F7 may be controlled so that:

The temperature of the premix fluids F7 within the premixing region(s) 6are below temperatures that would support their spontaneous combustion.In configurations where there is a physical partition 8 between thepremixing region 6 and the combustion regions 40 to 48, such temperaturecontrol may prevent flashback. In configurations where the premixingregion 6 is within the confines of the combustion chamber 2 so that nophysical partition separates the premix fluids F7 from the highcombustion reactivity in fluids F9 and F10, such temperature controldeters premature combustion before delivered fluids F4 are completelypremixed. Combustion prior to full premixing is preferably avoided todeter formation of localized pockets or regions within the combustionregion where the chemistry of the oxidant:fuel:diluent mix could resultin undesired phenomena such as high temperatures regions, andconsequently, high NOx formation rates.

When the premix fluids F7 are combined with the energized combustorfluids F9, they form an energized combustible fluid F10 that has atemperature that is preferably high enough to support its spontaneousstable combustion.

The fluid composition including diluent are preferably configured toachieve a desired adiabatic combustion temperature. The resultingtemperature of the energetic combustor fluids F9 is preferablycontrolled within a certain prescribed temperature range. Examples ofsuch temperature constraints include avoiding temperatures that supporthigh NOx formation rates, or operating at temperatures within designlimits for system hardware. E.g., the maximum temperature of turbineblades further downstream or the maximum temperature of adjacentcombustor walls.

The end of the primary combustion region may be characterized by a finaldelivery stage, wherein the remaining uncombusted fluids F4 of theprogressive combustion sequence are mixed with the energetic combustorfluids F9, forming the primary combustion region's 3 last batch ofenergized combustible fluids F10.

With continued reference to FIG. 1, the energetic combustor fluids F12formed in the last stage of the progressive combustion sequence may atfirst have high levels of UHC and CO. e.g., due to an incompletebreakdown and oxidation of UHCs to CO and insufficient CO oxidation toCO₂. These combustor fluids F12 exiting the primary combustion region 3are preferably delivered to one or more downstream equilibration regions4. These preferably have sufficient residence time for concentrations ofspecies in the combustion product fluids F12 to approach the equilibriumlevels corresponding to the local temperature and pressure of thesystem.

If the combustion product fluids F13 leaving the first equilibrationregion 4 have CO concentrations above target levels, a fluid controldevice 10 may be used to adjust the temperature of the combustionproduct fluids F13. The temperature is typically lowered, thusestablishing new lower equilibrium level for CO concentrations toapproach. A second equilibration region 5 may follow the first fluidcontrol device 10. Here sufficient residence time may be provided toallow the concentration of species in the combustion product fluids F16to approach lower equilibrium levels corresponding to the lower localtemperature and pressure of the system.

The fluid control device 10 may also incorporate a means to deliverfluids F11, typically oxidant and/or diluent fluids to the combustionproduct fluids F13. In addition to changes in fluid temperature andspecies concentrations, the equilibrium change device 10 may also resultin a change in fluid pressure. If further reduction in the concentrationof CO or another intermediate reaction species is desired after thesecond equilibration stage 5, one or more further fluid control devices11 may be used to adjust one or both of the composition and adiabatictemperature of the combustion product fluids F16. Further diluent orheat exchange may be provided to control the hot combustion fluidtemperature within or at the system outlet. (e.g. establishing turbineinlet temperatures). E.g., the hot fluid entering the expander ispreferably delivered at a temperature of at least 950° C. Accordingly,at the end of the progressive combustion and equilibration sequences,the concentrations of select species, especially NOx, CO and UHCs, arepreferably reduced to target levels.

FIG. 2 shows a schematic diagram of a preferred embodiment of acombustor 1 which has been used to experimentally validate some featuresof the progressive combustion aspects of the current invention. Thecross-sectional area of combustion regions is preferably increased withstreamwise distance. E.g., FIG. 3-FIG. 5 show sections A-A, B-B and C-Crespectively of the combustor embodiment of FIG. 2. These components anddimensions are exemplary and not prescriptive of the methodsdemonstrated.

For example, in the proof of concept embodiment shown, the combustorcomprises five concentric steel fire tubes 12-16, each of the fourlargest tubes having inlets 17-20 for air-steam-fuel mixture. Here, thesmallest fire tube 12 is configured as the upstream pilot end of thecombustor 1, and the largest tube 16 as the downstream exhaust end ofthe combustor 1. The inner diameters of the fire tubes preferablyincrease. E.g. tubes 13-16 are about 1.3 centimeters (0.5 inches), 2.5centimeters (1 inch), 5.0 centimeters (2 inches), 7.5 centimeters (3inches), and 10 centimeters (4 inches). Their lengths are approximately17.5 centimeters (7 inches) for the pilot fire tube 12, 80 centimeters(31 inches) for the exhaust fire tube 16, and about 23 centimeters (9inches) for the other three fire tubes 13-15. A plenum cap 21 isattached to the downstream end of the four smallest fire tubes. Theinner diameter of the cap 21 may be configured equal to the innerdiameter of the fire tube 12-15 to which it is attached. The cap's outerdiameter preferably fits within the inner diameter of the next largestfire tube 13-16. A fire tube plate 22-25 is attached to the upstream endof each the four largest fire tubes 13-16 with a circular opening ineach plate configured to allow the clearance of the next smallest firetube 12-15. Fluid plenums 26-29 are preferably formed by the spacebounded by the wall of a fire tube and its corresponding cap, and thewall of the next largest fire tube and its corresponding plate.Air-steam-fuel mixtures F4 may be fed into each plenum through one ormore inlets. E.g., two inlets 17-20 in each plenum. The mixtures mayexit the each plenum through orifices 30-38 that deliver the mixture tothe combustion regions 39-48 that define the inner chamber of thecombustor 1.

While particular orifices have been shown, numerous streamwise deliverylocations may be used. Similarly, continuous streamwise delivery slotsor porous walls may be used. These delivery methods permit thedistribution of delivery locations to be treated as a semi-continuous ora continuous distribution.

At the upstream end of the combustor 1, an air-steam-fuel pilot mixtureF5 may be fed to the system first by delivery through the pilot inlets17 to the pilot plenum 26. From the plenum 26, the uncombusted pilotmixture F5 may be fed to the pilot combustion region 39 through aperforated steel fire tube 12. The wall of the pilot fire tube 12 isperforated with numerous orifices. E.g., about 80 fairly equally spacedorifices 30-31 of diameter about 1.6 millimeters (0.0625 inches). Thefluid mixture delivered through 40 of these orifices 30 may impinge onthe hot surface of an igniter 49. e.g. a glow plug. The igniter 49, maybe powered by an external electric power source 50. It may be insertedinto the combustor 1. e.g., through the opening of the 2.5-centimeterfire tube plate 22 and secured there by means of a flange 51.

The fluid mixture delivered by the remaining 40 orifices 31 ispreferably delivered to the pilot combustion region 39 downstream of thepilot igniter orifices 30 and the igniter 49. The fluid mixturesdelivered by first the 40 orifices 30 are heated as they flow betweenthe igniter 49 and the perforated pilot tube 12. These fluids arepreferably heated to temperatures that support their self-ignition. Thisforms a pilot combustion region 39 just downstream of tip of the igniter49. Remaining pilot fluid mixture is preferably delivered progressivelyto the pilot combustion region 39 and mixed with the product fluidsformed from the combustion of previously delivered pilot fluids. Mixingelements may be provided. E.g., A steel coil 52 may be wrapped along theinner wall of the pilot fire tube 12. This enhances mixing within thepilot combustion region 39 and has a thermal mass and bluntness thathelps act as a flame holder, thus improving the stability of the pilot.

The combustion product outflow F20 of the pilot combustion region 39 isequivalent to the inflow of the stage 1 combustion region 40. Anincreasing number of orifices are preferably configured along thestreamwise increasing direction. E.g., Four orifices 32, about equallyspaced at 90 degrees from each other in the same axial plane, permitfluid communication between the stage 1 plenum 27 and the stage 1combustion region 40. The air-steam-fuel mixture F4 is preferablydelivered to the stage 1 combustion region 40 through the four stage 1orifices 32. The delivered mixture is preferably energized by the inflowF20 to the stage 1 combustion region 40, sufficiently to support thecombustion of the uncombusted mixture delivered at this location.

The combustion product outflow F21 of the stage 1 combustion region 40is equivalent to the inflow of the stage 2 combustion region 41. Similarto Stage 1, about twelve orifices 33-35 allow fluid communicationbetween the stage 2 plenum 28 and the stage 2 combustion region 41. Thetwelve orifices 33-35 of stage 2 are may be divided into 3 sets of 4orifices. The four orifices comprising a set are preferably placed inthe same axial plane, preferably oriented with about an equal spacing of90 degrees from each other. Each orifice set may be axially separated byapproximately 3.8 centimeters at ambient conditions.

In this configuration, the orifices 33-35 protruded about 6 millimetersinto the stage 2 combustion region 41. Generally speaking, theair-steam-fuel mixture F4 delivered to the stage 2 combustion region 41through the stage 2 orifices 33-35 is energized by the inflow F21 to thestage 2 combustion region 41, supporting its combustion. e.g.,uncombusted mixture delivered through the four orifices 33 of the mostupstream of the three orifice sets, is energized by the inflow F21 tothe stage 2 combustion region 41. This forms the first combustion region42 of three stage 2 micro-combustion regions 42-44. The subsequentcombustion products from the first micro-combustion region 42 arepreferably used to energize the uncombusted mixture delivered throughthe second set of orifices 34. Likewise, the combustion products fromthe second micro-combustion region 43 of stage 2 are preferably used toenergize the uncombusted mixture delivered through the third set oforifices 35. The outflow of the third micro-combustion region 44 isequivalent to the overall combustion product outflow F22 of the stage 2combustion region 41.

The combustion product outflow F22 of the stage 2 combustion region 41is equivalent to the inflow of the stage 3 combustion region 45.Similarly with previous stages, eighteen orifices 36-38 allow fluidcommunication between the stage 3 plenum 36 and the stage 3 combustionregion 45. These eighteen orifices of stage 3 may be divided into 3 setsof 6 orifices 36-38. The six orifices comprising a set are placed in thesame axial plane, being oriented with about an equal spacing of 60degrees from each other.

In this configuration, each set of orifices is axially separated byapproximately 3.8 centimeters. The orifices 36-38 protrude approximately6 millimeters into the stage 3 combustion region 45. Generally speaking,the air-steam-fuel mixture delivered to the stage 3 combustion region 45through the stage 3 orifices 36-38 is energized by the inflow to thestage 3 combustion region 45, supporting its combustion. Morespecifically, uncombusted mixture delivered through the six orifices 36of the most upstream of the three orifice sets, is typically energizedby the inflow to the stage 3 combustion region 45, forming the first 46region of three stage 3 micro-combustion regions 46-48. The subsequentlycombustion products from the first micro-combustion region 46 arepreferably used to energize the uncombusted mixture delivered throughthe second set of orifices 37. Likewise, the combustion products fromthe second micro-combustion region 47 of stage 3 are preferably used toenergize the uncombusted mixture delivered through the third set oforifices 38. The outflow of the third micro-combustion region 48 isequivalent to the overall combustion product outflow F23 of the stage 3combustion region 45.

The combustion product outflow F23 of the stage 3 combustion region 45is equivalent to the inflow of the burnout and equilibration region 4.The 4-inch diameter fire tube 23 surrounding the burnout andequilibration region 4 is preferably insulated. E.g., it is wrapped withapproximately 1.5 inches of ceramic fiber insulation 53 to minimizeundesired heat losses from the burnout and equilibration region 4. Theoutflow of the burnout and equilibration region 4 is equivalent to theexhaust of the combustor 1.

FIG. 6 shows a representative centerline temperature profile measuredfrom experiments performed with the proof of concept combustorembodiment of FIG. 2-FIG. 5. TABLE 1 shows input conditions for theresults shown in FIG. 6. TABLE 1 Fuel Propane - C₃H₈ Temperature ofDelivery to Pilot 125° C. Temperature of Delivery to Stage 1 127° C.Temperature of Delivery to Stage 2 136° C. Temperature of Delivery toStage 3 128° C. Relative Stoichiometric Ratio of Pilot - Lambda-p 1.22Relative Stoichiometric Ratio of Stage 1 - Lambda-1 1.22 RelativeStoichiometric Ratio of Stage 2 - Lambda-2 1.22 Relative StoichiometricRatio of Stage 3 - Lambda-3 1.22 Water to Fuel Ratio of Pilot - W-p 1.0Water to Fuel Ratio of Stage 1 - W-1 7.1 Water to Fuel Ratio of Stage2 - W-2 7.1 Water to Fuel Ratio of Stage 3 - W-3 7.1 Ignitor Power 150 WFraction of Total Volumetric Flow to Pilot 11% Fraction of TotalVolumetric Flow to Stage 1 34% Fraction of Total Volumetric Flow toStage 2 22% Fraction of Total Volumetric Flow to Stage 3 33% OverallWater to Fuel Ratio - W-tot 6.3 Overall Relative Stoichiometric Ratio -Lambda-tot 1.22 Total Flowrate 150 slpm

With further reference to FIG. 6, after the pilot region, the averagetemperature during the progressive combustion sequence ranges from about650° C. to 950° C., with an average of about 800° C. Each minimum in thetemperature profile is located approximately 1 to 2 centimetersdownstream of the corresponding delivery location. The minima in theprofile are due to convective energy transfer from the energeticcombustor fluids to the recently delivered premix fluids. Temperaturesof the magnitude shown in FIG. 6 are significantly lower than thetemperatures that are conventionally believed to be necessary to achievestable combustion. Furthermore, such low temperatures are expected toresult in low NOx formation.

FIG. 6 also shows the NOx and CO concentrations in the burnout andequilibration regions of the combustor with the relative stoichiometricratio of the pilot, Lambda-p, set to 3.5. These results demonstrate theability to achieve CO and NOx concentrations of about 3 ppm or less forboth species. Low NOx levels are generally expected for such lowtemperatures. However, CO levels are commonly expected to be very highunder low temperature combustion conditions. Just downstream of the lastdelivery location at about 43 centimeters, CO levels are initially veryhigh, on the order of 100 ppmv to 1000 ppmv due to the incompleteburnout of recently delivered fuel. As one progresses downstreamhowever, CO levels fall significantly with an eventual asymptote ofabout 3.5 ppm. The results of this experiment demonstrate that very lowCO levels can be achieved with the implementation of the progressivecombustion method.

FIG. 7 shows the dependency of exhaust NOx levels to the water-to-fuelratio of the pilot, while keeping the inputs to the remainder of thesystem constant. As more water is added to the pilot the concentrationof NOx in the exhaust (downstream of the progressive combustionsequences) decreases. This is generally expected as more water resultsin a lower flame temperature in the pilot, resulting in lower rates ofthermal NOx formation. FIG. 7 also demonstrates for these conditions,most of the NOx in the system is likely formed in the pilot wheretemperatures are highest, suggesting that the progressive combustionsequence as demonstrated here, results in sub-ppm levels of NOx due tothe low temperature achievable during the combustion process.Consequently, sub-ppm levels of NOx may be achievable for the overallcombustor provided that it is configured with a pilot that has low NOxlevels.

FIG. 8 depicts an embodiment of the current invention configured andcontrolled with progressive delivering and combusting of an uncombustedfuel-oxidant-diluent mixture at five different mixture delivery rates.It shows the combustor fluid temperature, the CO concentration, andrelative fluid delivery rate versus progressive combustion along thestreamwise distance. This shows preferable configurations with twoinherently stable combustion delivery rates (A and B), and two otherpossible conditionally stable delivery rates (C and D), compared with anunstable delivery rate (E).

For the five cases shown, uncombusted fluid is delivered over a lengthL_(D) into a combustor of length L_(C). The uncombusted fluid isdelivered at a mass flow rate M_(D) per unit length of the combustor.Energetic combustor fluid flows into a region at a mass flow rate M_(E).The uncombusted fluid and energetic fluid mix to form a mixed combustionfluid within the region. Some fuel and oxidant combust in a region,heating the mixed fluid, forming energetic fluid and delivering it intothe next region.

The fluid delivery along the streamwise dimension of the combustor fromthe upstream end to L_(D), the delivery flow ratio R of M_(D) to M_(E)is preferably configured and controlled to be approximately constant inthese configurations. Consequently, these cases are characterized byapproximately exponentially increasing delivery flow rates M_(D) andmass flow rates M_(E). Five different ratios R of mass delivery flowratio of M_(D) to M_(E) are shown, with consequent differences in thetotal quantity of fluid delivered, which is proportional to the areaunder each delivery profile curve.

In each of these five cases, the chemical compositions of the delivereduncombusted fluid mixture are modeled as about the same, resulting inabout the same adiabatic combustion temperature T_(ADIAB). (i.e., thefinal fluid temperature after the uncombusted fluid is caused to befully combusted with no heat loss). In these configurations, the hot orenergetic pilot fluid is preferably delivered into upstream end of theprogressive combustion region. In these models, the hot pilot fluid isassumed to have about the same composition and to be at the adiabaticcombustion temperature T_(ADIAB) that would result from adiabaticallycombusting the delivered uncombusted fluids. The temperatures of thedelivered uncombusted fluids T_(DEL) are preferably lower than theself-ignition temperature T_(IGN) of the combusting fluids.

The neutrally stable configuration B is preferably configured for andcontrolled at about the critical fluid delivery flow ratio R_(CRIT),which by definition separates the inherently stable delivery condition,such as configuration A, from the conditionally stable condition, as inconfiguration cases C and D (in contrast to the unstable configurationE). This critical flow rate ratio R_(CRIT) of Case B is the maximumprogressive flow rate ratio possible which can be maintainedindefinitely in a given configuration. Under such conditions,maintaining the flow rate ratio R_(CRIT) results in an approximatelyexponentially increasing fluid delivery profile. This can be nominallymaintained over an unlimited length of the reactor (beyond L_(D))without quenching combustion at a mean temperature of the mixedcombusting fluid at or greater than T_(CRIT).

For configurations with hot fluid entering the combustion region at atemperature greater than T_(CRIT), progressively delivering uncombustedfluid at the flow ratio R_(CRIT) will maintain the mean mixed combustingfluid temperature greater than or equal to T_(CRIT) (decliningasymptotically towards T_(CRIT) in successive combustion regions). Forhot combustion fluid delivered into one of the combustion regions atT_(CRIT), delivering uncombusted fluid into that and later regions atthe critical fluid delivery ratio R_(CRIT) will maintain the mean mixedfluid temperature at T_(CRIT) in that and successive combustion regions.

Preferably delivering uncombusted fluid in configuration B at thecritical fluid delivery ratio R_(CRIT) under adiabatic combustionprovides the highest sustainable delivery ratio R_(CRIT-MAX) to sustainmixed combusting fluid temperature T_(CRIT) when hot fluid is deliveredinto the combustion regions at T_(CRIT). With increasing heat loss tothe surroundings, the uncombusted fluid is preferably delivered at acritical flow delivery ratio R_(CRIT) that is progressively lower thanR_(CRIT-MAX) and which declines in proportion to the heat loss rate.

Some embodiments may be preferably configured and controlled toprogressively deliver uncombusted fluid at a flow ratio R_(PC) less thanthe critical flow rate ratio R_(CRIT) giving an inherently stableconfiguration depicted as case A. For such inherently stableconfigurations A, the combustion fluid temperature is typically greaterthan and approaching a mean temperature of sustained progressivecombustion, T_(PC), which is greater than the equivalent mixed fluidtemperature for the critical case T_(CRIT) at the critical flow rateratio R_(CRIT). With preferable configurations like A, if the hot fluidenters a combustion region at T_(PC), then delivering uncombusted fluidat the ratio R_(PC) above R_(CRIT) will maintain the fluid temperatureat T_(PC).

To preferably maintain the combustion fluid at a mixed fluid temperatureT_(PC) above the mean fluid critical temperature T_(CRIT), at least therate of diluted fuel-oxidant mixture is preferably controlled tomaintain the fluid deliver ratio R_(PC) less than the correspondingcritical delivery flow rate ratio R_(CRIT) of delivered fluid mass flowrate to hot combustor fluid flow rate.

For inherently stable configurations A or the neutrally stableconfiguration B, the hot combustion fluid temperature exiting one ormore combustion regions is preferably controlled to be at least greaterthan or equal to T_(CRIT) by configuring and controlling the uncombustedfluid deliver rate ratio at a level that is less than or equal toR_(CRIT). In such preferable inherently or neutrally stableconfigurations, combustion provides specific molar heat release rates(by combustion of the combustible gases per minimum stoichiometry ofmaterial) that deliver heat at about equal to the rate of enthalpychange due to formation of the products of combustion relative to theuncombusted fluid, plus the rates of enthalpy absorbed by any diluents(including diluents within the fuel and oxidant mixture, any diluentfluids added, and any oxidant fluids or fuel fluid in excess of thestoichiometric ratio) plus any rates of net heat loss (or minus any heatgain) from the surrounding walls, regions, and upstream and downstreamcombustion regions.

These models assume continuous delivery, or pseudocontinuous deliverythrough numerous orifices, with corresponding rapid mixing. Realcombustor may have more discrete flows and slower mixing rates.Accordingly, configurations are preferably configured to control flowdelivery ratios in a range from a lower ratio to an upper ratio. Thisresults in the combusting fluid temperature being controlled between alower and an upper mixed fluid temperature.

For example, fluid delivery ratio is preferably controlled betweenR_(PC) and ratio R_(CRIT) to preferably control the mean combustingfluid temperature in an inherently stable sustainable fashion betweenT_(PC) and T_(CRIT). Since the allowable flow delivery ratio is zero atT_(ADIAB), the flow delivery ratio R_(PC) is preferably controlled toless than 90% of the range between T_(CRIT) and T_(ADIAB). For higherinherently sustainable flows, the ratio R_(PC) is preferably controlledbetween 33% and 99% of R_(CRIT) and more preferably between 67% and 95%of R_(CRIT).

In some configurations, the fluid delivery may be configured forconditionally stable operation by providing an uncombusted delivery flowdelivery ratio R_(CS) greater than the critical flow delivery ratioR_(CRIT). Such higher flow delivery rates R_(CS) result in conditionallystable combustion as exhibited in cases C and D or in eventuallyunstable combustion as shown in configuration E of FIG. 8. Progressivelydelivering fluid at the fluid delivery ratio R_(CS) results in anexponentially increasing fluid delivery profile that would eventuallyquench the combustion process. Mixing cooler delivered uncombustedfluids with the combusting fluid at such delivery ratios R_(CS) coolsthe combustion toward the temperature of the delivered uncombustedfluids, T_(DEL). This eventually drops the combusting fluid temperaturebelow the ignition temperature T_(IGN) as depicted in FIG. 8 case E.

With further reference to FIG. 8, in configurations with conditionallystable delivery rates R_(CS) above R_(CRIT) has reduced the fluidtemperature below T_(CRIT) the uncombusted fluid delivery is preferablystopped or more preferably reduced to below R_(CRIT) while the mixtureof uncombusted and combusting fluid is still above its self-ignitiontemperature. E.g., to R_(PC). This allows the combustion process to berejuvenated to a higher temperature, preferably above T_(CRIT).Configurations are preferably configured and controlled to at leastavoid letting the temperature of progressive combustion fall below theself-ignition temperature T_(IGN). (i.e., the blowout condition shown incase E). In such a blowout condition, there is little or no possibilityof the combustion process being rejuvenated after the end of uncombustedfluids delivery. Such blowout conditions are preferably avoided tosustain stable combustion in the present invention.

When the progressive delivery of uncombusted fluid is stopped inconditionally stable configurations such as C and D, the temperature ofthe hot combusting fluid system will rise toward the adiabaticcombustion temperature, T_(ADIAB). When the progressive delivery isreduced from R_(CC) to a fluid ratio R_(PC), the combustion fluidtemperature will rise back towards T_(PC). As desired, combusting fluidtemperatures generally below T_(CRIT) may conditionally maintained byalternating fluid delivery rates between levels above and belowR_(CRIT). This is preferably combined by weighting the relative durationof the higher and lower flow rates. E.g., the time at R_(CC) relative totime at R_(PC).

With further reference to the conditionally stable cases C and D of FIG.8, when the combustion process are rejuvenated, a configuration mayprovide for the end of the combustor to occur before full fuelconversion is approached. In such cases D, CO concentrations remainrelatively high. E.g., above about 100 ppmv. In other configurations,the combustor is preferably extended to provide further residence timeand burnout of unburned hydrocarbons and CO, as shown in configurationC. e.g., with CO below about 10 ppmv. This distinguishes betweenconditionally stable combustion with burnout as in case C, versus aconditionally stable configuration without burnout as in case D.

In some configurations, one or more of the delivery flow ratio orcomposition of fluid delivered into a region may be desirably controlledto adjust the adiabatic temperature of the mixed composition in one ormore regions. For example, the adiabatic temperature may be constrainedto limit formation of combustion byproducts such as NOx, as depicted inFIG. 13 by staying outside of the lower central region.

Similarly, the delivery flow ratio or fluid delivery composition may becontrolled to adjust the mixed fluid composition within one or moreregions. For example, configurations may be desirably configured forrich combustion or partial oxidation as shown in FIG. 15. In suchsystems, the oxidant/fuel ratio is configured to below thestoichiometric ratio. This oxidant/fuel ratio Lambda is preferablyconfigured above the coke or soot formation level. E.g., Lambda>0.5 or0.6. More preferably, both the water/fuel and air/fuel ratios areadjusted to constrain soot formation below a desired level.

With further reference to conditionally stable cases C, D (or theunstable case E), while unlimited exponentially increasing deliverywould eventually quench the combustion process, in some configurationsthe delivery profile may be configured with multiple delivery regionsinterrupted by periods of lower delivery ratios less than R_(CRIT), orno delivery. During the periods of lower or no delivery ratios, thecombustion process is allowed time to rejuvenate, thus keeping thesystem within a pseudo stable state. This is analogous to discretestaged Progressive Combustion, in that delivering a finite amount offluid at each delivery location is nominally similar to having arelatively high fluid delivery ratio. However, when the amount added ateach location is constrained and has a finite rate of mixing with thecombusting fluid, this is like interrupting delivery or spreading outthe fluid delivery preventing the combusting fluid temperature frombeing reduced to quenching conditions.

To control the temperature within a range that is bounded by a lowertemperature below T_(CRIT) (and above T_(IGN)) the flow rate ispreferably controlled in a time weighted combination of delivery flowratios both above and below R_(CRIT). E.g. between a range from 25% to150% of R_(CRIT). The delivery flow ratio of uncombusted fluid to hotcombustion fluid may similarly be controlled such that the progressivestreamwise integral from an upstream region inlet to a downstream regionis at least greater than the delivery flow ratio required to maintainignition. Preferably the delivery flow ratio is maintained to provide atemperature about 33% of the way between the ignition temperatureT_(ING) and the adiabatic combustion temperature T_(ADIAB).

Preferably this streamwise integral of the delivery flow ratio iscontrolled within a range about the corresponding progressive streamwiseintegral for the respective critical flow delivery ratios in thecombustion regions. Controlling the flow delivery ratio may similarly beused to control the fluid temperature within a temperature range aboutthe critical temperature T_(CRIT). Where fluid delivery compositionvaries in the streamwise direction, this integral will further accountfor such variations and the corresponding changes in the ignitiontemperature, adiabatic temperature, and critical temperature, andcorresponding critical delivery flow ratio. More preferably, thisstreamwise integral of the delivery flow ratio is maintained at lessthan or equal to the streamwise integral of the critical delivery flowratio sequentially within each region. This maintains inherently stablecombustion.

To increase combustion stability of a Progressive Combustion system forthe same amount of fluid delivered, some configurations preferablyreduce the rate of delivery and distribute it over a longer length ofthe combustor both with continuous or staged-discrete delivery. Thismethod of delivering fuel, oxidant and diluent fluids is complemented bycontrolling for other methods. For example, these additional concernspreferably include one or more of (1) the degree of combustionstability, (2) controlling pollutant removal such as CO, (3)controllingpollutant formation such as NOx, (4) controlling the adiabatictemperature of the diluted mixture, and (5) the overall constraint onthe physical size of system.

FIG. 9 graphically depicts the results of some time-based numericalequilibration regimes. These simulations show the effects of a range ofequilibration region temperature control methods on the concentrationsof CO and Nitric Oxide (NO) in the combustion product fluid after theprimary combustion region. NO is shown as representative of all theoxides of nitrogen (NOx). These results are numerical computationsutilizing the comprehensive iso-octane oxidation mechanism published byCurran et al. (2002).

The combustible fluid modeled comprises iso-octane as fuel fluid, andair as the oxidant fluid provided in about a 5% excess of stoichiometricflows. Water is preferably used as diluent fluid. E.g., being set atabout 3.15 times the fuel mass. Primary combustion is modeled asoccurring at about 30 atm. At the end of the combustion period, thecombustion product fluids are at 1500° C.

About 1 ms after the final quantities of uncombusted fluid is deliveredto the combustor, the combusting fluid reaches a nominallypost-combustion state at the beginning of the equilibration region. Herethe CO concentration is about 28 ppm and the NO concentration is about1.6 ppm.

To demonstrate the impact of some embodiments of controllingequilibration conditions, a variety of temperature controls areimplemented after 1 ms for an equilibration period, while maintainingthe pressure at about 30 atm. For these models, temperature controls maynominally be implemented by isobarically transferring energy to or fromthe system.

In configurations A, B, C and D, the equilibrating fluid temperature isnominally changed or stepped very rapidly from 1500° C. to about 900°C., 1100° C., 1200° C. and 1300° C., each step being followed by anequilibration residence time in an equilibration region in which thetemperature is held about constant. By comparison, in configurations Eand F, the equilibration temperature first steps very rapidly to 1300°C. followed by a more gradual decrease in the equilibration temperature.The temperature profiles in the cases E and F are shown as aboutlog-linear with temperature declining linearly versus log-time.

With further reference to the lower graph in FIG. 9, the correspondingCO concentration responses are shown for these configurations. For thetemperature step-isothermal configurations A, B, C and D, the CO removalrate immediately after the step is highest in case D with the hottestisotherm at 1300° C., and lowest in case A with the coldest isotherm at900° C. Intermediate configurations B and C have intermediate rates.

Configurations A, B, C and D, show that while higher temperaturesinitially favor higher CO removal rates, higher temperatures also resultin higher CO equilibrium levels. This is due to greater dissociation ofcarbon dioxide at higher temperatures. For example it may take over 20ms for CO concentrations to be reduced to approximately 3 ppmv at 900°C., while it may only take about 1 ms at 1300° C. However, after about100 ms at 1300° C., the CO concentration remains its equilibrium valueof about 3 ppmv. By contrast, for the 900° C. case, the CO concentrationafter 100 ms may drop over 100 times to about 8 ppbv while approachingits equilibrium level of near 3 ppbv.

Changes in NO concentration for several different temperature controlsare also shown in FIG. 9. For the cases shown, the NO concentration ofabout 1.5 ppm that was established further upstream during the primarycombustion process at 1500° C., was not significantly changed during anyof the subsequent equilibration temperature controls methods.

With continued reference to FIG. 9, cases E and F demonstrate otherequilibration temperature profiles (apart from step-isotherm sequences)that result in faster responses in CO concentration reduction to targetlevels. The factor of improvement in response time generally increaseswith lower final temperatures or lower target CO levels. For example,for a CO target level of about 1 ppm a gradually decreasing temperatureprofile of condition E results in the realization of the target COconcentration in about 85% of the time it would take for the beststep-isothermal option.

For a target CO of about 0.2 ppmv, case E is able to reduce the time toapproximately 75% of the best step-isothermal option. In keeping withthis trend, for 10 ppbv, case F reduces the response time to about 40%of the best step-isothermal option. The slower temperature gradient caseF initially drops the CO rate slower than the faster gradient case E.However to achieve lower CO emissions lower than 10 ppbv, there comes atime when the slower gradient F reduces CO emissions faster than case E.

The desired emissions levels may be adjusted according to pertinentregulations. E.g. 50 ppmvd, 25 ppmvd, 9 ppmvd, or 2.7 ppmvd, convertedto a 15% O₂ basis. More preferably, the emissions with power systems arepreferably configured to an output based parameter. E.g. NOx massemissions per shaft power out: <500 mg/GJ for <3 MWe; <240 mg/GJ, andfor 3 MWe to 20 MWe and <120 mg/GJ for >20 MWe. For more stringentemissions, these levels could be reduced to about 0.032 kg/MWhe.

In comparing the benefits of temperature steps and the greater benefitsof temperature gradients, more preferred embodiments may be configuredwith a continuous curvilinear variation in the temperature gradient.“For a given fluid composition, there may be a preferred fluidtemperature which gives a more rapid rate of decline in COconcentrations. i.e., a higher temperature would result in slower rateof CO reduction due to higher carbon dioxide dissociation, while a lowertemperature would give a slower rate of CO oxidation reaction. Inconsidering a streamwise sequence of fluid compositions, there may be apreferred local fluid temperature gradient which gives a preferred COoxidation rate for the locally changing fluid composition.”

Accordingly, a hypothesized embodiment may be configured for an optimumtemperature profile, which continuously optimizes the local temperaturegradient. This lowers the temperature with increasing residence time,thus optimizing the CO oxidation rate. Such a method may result in acompact embodiment, reducing CO more rapidly to target levels. Thishypothesized embodiment is schematically estimated and shown asconfiguration G in FIG. 9.

This time-dimensional perfectly mixed analysis may readily be extendedto two and three dimensional models to provide more realistic spatialand temporal distributions. The configuration method is preferablyadjusted to accommodate the increased times required for realcombustion, turbulence, mixing and evaporation rates. These improvedresults may be used to refine the equilibration methods described above.e.g., of using sequential or progressive equilibration regions withstepped, ramped or continuously varying temperatures, temperatureranges, or temperature profiles optionally coupled with one or moreequilibration volumes and residence times.

With reference to FIG. 10, some configurations may control one or bothof the temperature and residence times of the equilibration regionswhile accounting for the water to oxygen ratio in the energeticcombustor fluid. FIG. 10 schematically approximates control methodsshowing desired CO concentration versus the suggested equilibrationtemperature for the water-diluent system as modeled in FIG. 9. Similarcontrol methods, approximately graphically parallel to the relationshipsof FIG. 10, may be applied for different combustion systems comprisingcarbon-based fuels, and various oxidant and diluent fluids. Asdemonstrated in less-water/more-air and more-water/less-air cases, ifexcess air displaces water as the primary diluent, the suggestedequilibration temperature is higher for a given target CO concentrationand vice versa.

For the configuration modeled in FIG. 10, the combustion product fluidsmay be brought to near the equilibration temperatures corresponding tothe target CO levels indicated in the figure. This may use one or moreof the equilibration configuration methods described above to approachthe desired temperature profile. With further reference to FIG. 10,similar relationships between the best equilibration temperature and thedesired emissions concentration at a given residence time may beobtained for mixed fluid diluents comprising air and water or similarfluids with other fluids comprising one or more of nitrogen, water,carbon dioxide and/or oxygen. Generally speaking, as water or steamdisplaces excess air as a primary diluent, target CO levels may beachieved at lower temperatures.

One or more of 1) diluent addition, 2) heat exchange, 3) flowacceleration, and/or 4) expansion or work extraction may be used incontrolling the temperature of the equilibrating fluid within one ormore equilibration regions. For example, FIG. 12 conceptually depicts avariety of sets of embodiments for temperature control in equilibrationregions, using one. These control methods are conceptually depicted ascovering temperature regions such as 900° C., 1100° C., 1300° C., 1500°C. and 1700° C., within the range of turbine inlet temperatures thatcharacterize current and future levels of turbine technologies.

Each of these temperature control methods may be utilized individuallyor in any combination with any of the others, at any of these or othertemperature ranges. The diluent addition and/or heat exchange methodsare nominally shown as being variously applicable to the fulltemperature range. While it may be used at lower temperatures, theexpander method, FIG. 11, is shown as being capable of handling higherturbine inlet temperatures such with energetic fluids in advancedturbines at about 1700° C. At such temperatures, the equilibrium COconcentrations are substantially higher than the desired system exitconcentrations.

Accordingly the temperature reductions and efficiencies desiredpreferably involve utilizing expanders with one or more equilibrationregions after the first and/or subsequent expander(s) where temperaturesare appropriate for the equilibration and residence time desired toachieve the desired reductions in CO emissions. Where multiple turbinestages are used to reduce the energetic fluid temperature from theturbine inlet temperature (TIT) to the desired lowest equilibrationtemperature (e.g. from 1500° C. to 1200° C.), then multipleequilibration regions are preferably used over a single stepequilibration region. These can be configured for faster equilibrationand thus shorter and more compact equipment than a single step.Downstream equilibration regions are preferably longer than the intakeresidence times.

FIG. 11 shows a representative embodiment of a gas turbine powergenerating system utilizing the Progressive Combustion and Equilibrationstrategies to control emissions. This uses a combustor 1 comprising a(contiguous) primary combustion region 3 and an optional equilibrationregion 4 as described in FIG. 1. This embodiment may use one or moreinterstage equilibration regions 5 within the turbine to further reduceCO concentrations at the lower temperatures resulting from partialexpansion of the combustion gases.

Progressive combustion as described in conjunction with FIG. 1 occurs inthe ‘primary combustion region’ 3 a portion of the combustor 1. Thesource for the oxidant fluid F1 may be a blower, a compressor or acompressor system 63. For example, uncompressed air F6 may be modified,humidified, enriched with oxygen, or diluted, prior to, during, or aftercompression. This may include wet compression with a water mistentrained into the compressor inlet, or delivered within the compressor.Exhaust gas may also be recirculated and compressed along withatmospheric air F6. As discussed in FIG. 1, other inputs to the primarycombustion region 3 include one or more fuel fluids F2 and one or morediluent fluids F3.

Combustion product fluids from the primary combustion region 3 may passthrough one or more optional equilibration regions 4-5, where COconcentrations are reduced by controlling one or more of the fluidtemperature, and/or residence time (as discussed above). Further oxidantF1 or diluent F3 may be added at this point as part of the temperaturecontrol, and to refine stoichiometry to provide a beneficial oxidantconcentration in the equilibration region.

With reference to FIG. 16, in some embodiments, fluid temperatures at anintermediate region in the power system would result in equilibrium COconcentrations above a desired CO outlet concentration. E.g., at theoutlet of a high pressure combustor feeding hot combustor fluid into theinlet of a turbine. The fluid temperatures would preferably be reducedalong a curvilinear temperature path to provide rapid CO reduction.E.g., a hypothetical path G such as described above and shown in FIG. 9,and in FIG. 16.

As schematically depicted in FIG. 16, expansion through an expansionstage of a work engine is relatively rapid. This configuration nominallyshows hot fluid flowing from an equilibrating region 4 into a turbineinlet with a temperature of about 1400° C. The hot fluid temperature canbe approximated by a step drop in temperature, or preferably as a rapidcurvilinear temperature gradient or profile. E.g., stages 58, 59, 60 ina turbine or reciprocating engine. Where available expansion equipmentexpands the fluid faster than the desired curvilinear temperature path,the temperature may be reduced along a more rapid a curvilinear pathwith one or more expanders to one or more desired holding temperatures.E.g. as shown by path H in FIG. 16 or as in paths C, or D, in FIG. 9. Atleast one of the expansion stages 58, 59, 60 is preferably followed byat least one equilibrating region 5. The volume of the equilibratingregion is preferably configured relative to the fluid flow rate toprovide an equilibrating residence time to further oxidize the CO toCO₂.

For example, with reference to FIG. 11, in some configurations, thepressurized, partially equilibrated combustion gas F13 is expandedthrough a first turbine expander 58, producing partially expandedcombustion gases F14. As is typical in a gas turbine, the first turbine58 may be used, via a shaft 61 or other energy transfer means, to driveone or more compressors 63, and possibly a load such as electricgenerator 55. Some configurations may configure equilibration regionsbetween turbomachinery stages configured along a common shaft. Themechanical shaft power or electrical power produced is preferably usedfor mechanical drive applications or energizing a user load or toconvert electricity to at least one of mechanical power, light, addingheat, or removing heat. This method further uses the power system topreferably transmit the electricity generated over distances exceedingabout 8 km or 5 miles.

Implementing the progressive combustion and equilibration strategiesherein described, may, in some configurations, require a larger thanconventional combustor 1 to provide a greater residence time. Suchlarger residence times may be required with high diluent concentrationswhere the oxidant concentration is preferably reduced to nearstoichiometric concentrations (for example from about 15% excess oxygento about 5% excess oxygen).

The larger compressor combustor 1 may involve a greater separationbetween compressor 63 and first turbine expander 58. In such aconfiguration, one or more additional bearings 56 may be required tocontrol shaft vibrations. A larger thrust bearing or additional thrustbearings 57 may also be required to accommodate a thrust differentialdue to the use of significant quantities of diluent F3 in the combustor1 with correspondingly lower oxidant fluid F1, compared withconventional lean combustion turbines.

Where an equilibration region 5 is configured between two turbineexpansion stages one or more shaft stabilization bearings 56 may beadded to control vibrations of a long shaft 23. e.g., between one orboth of expander stages 58 and 59, and between expander stages 59 and60. These bearings may be mounted on stators between expansion stages.Such bearings 56 are preferably protected from the hot fluid and cooledwith diluent to enable operation near the high temperature flows. Theheated diluent is preferably recycled into the progressive combustionsystem.

As a result of the work extracted in the first turbine expander orexpander stage 58 the partially expanded combustion gas F14 will becooler than the partially equilibrated combustion gases F13 produced bythe combustor 1. The resulting cooler more equilibrated combustion gasesF16 are then preferably expanded through a second turbine expander stage59. These cooler gases may be passed through a second interstageequilibration region 5 within a turbine section for at least a seconddesired interstage residence time. This takes advantage of these lowertemperatures to further reduce the CO concentrations towards the newlower equilibrium CO concentrations at this lower temperature. Thesecond interstage residence time may be larger than the first interstageresidence time to accommodate the slower CO reaction rate at the coolertemperature, depending on the degree of reaction desired relative to thetemperature. In such equilibration regions, at least 75% of thetemperature reduction occurs in less than 50% of the streamwise fluidpath length of that equilibration region.

With reference to FIG. 9, uses an equilibration residence time of atleast 0.5 ms is desired for the reaction at about 1500° C. Consideringconfiguration D, an expansion with temperature drop from 1500° to 1300°C. may use an equilibration residence time of at least 0.7 ms, andpreferably at least 1 ms. Similarly, configurations C, E, F and G mayuse a residence time of at least 1.5 ms, and preferably 3 ms to reducethe CO to below 1 ppmv. These models are for near stoichiometriccombustion. E.g., about 1.05 Lambda. E.g. the NOx output is preferablycontrolled to less than about 2.7 ppmvd at 15% O₂ for combustion systemor to 0.032 kg/MWh in a power system.

This interstage equilibration region 5 may also include a fluid controldevice 10, including the addition of further diluent F15 such aspressurized steam from a Heat Recovery Steam Generator (not shown). Thissecond turbine expander stage 59 may variously be coupled via a powershaft 62 to one or more load devices such as a generator or anothercompressor (not shown). One or more additional turbine expander stages59 as well as other equilibration stages 5 and fluid control devices 11may be included further downstream before combustion gases are fullyexpanded. Some of the remaining thermal energy in the fully expandedcombustion gases F25 may be recovered by producing steam such as with aHeat Recovery Steam Generator (HRSG) (not shown) and/or hot water withan economizer heat exchanger, for use as one or more of the diluent,oxidant or fuel fluids in this system F1, F2, F3, F11, F15, and for useas a diluent F3 or as modifier of the oxidant fluid F1 or the fuel fluidF1.

Again with reference to FIG. 12, the flow acceleration methods oftemperature control are nominally shown to cover moderate to hightemperatures where they are most effective. (They could also be used atlower temperatures.) As noted, the flow acceleration and expandermethods can be used together as well as with diluent cooling and/or heatexchange methods. Such a heat exchanger preferably provides at least 10%of the temperature reduction provided in the equilibration regions. Suchheat exchangers preferably use diluent to remove the heat. The heateddiluent is then preferably delivered upstream into the progressivecombustion or equilibration regions. It may be delivered downstream intoan equilibration region.

The internal volume of each of these equilibration regions may furtherbe individually configured to adjust the residence time undergone by theequilibrating fluid within each of those equilibration region. E.g., thecross sectional area and flow length. Existing residence time betweenone or more expansion stages is preferably accounted for whenconfiguring the additional volume desired for the residence timedesired. For example, in many turbines, an aerodynamic member iscommonly provided to redirect the expanded flow to one or both of apreferred direction and a preferred velocity. The residence time of thefluid passing through such stators or vanes is preferably accounted forand subtracted from the desired residence time when configuring theadditional residence volume.

The residence time provided after cooling with the expander ispreferably at least 50% of the residence time of the fluid expandingthrough the expander stage. In some configurations, the residence timeis preferably at least 175% of the turbine transit time. This preferablyincludes and is greater than the flow time through any stator or vane.

The temperature and/or residence times in the individual equilibrationregions may further be configured in various combinations to achieve thedesired concentrations of one or more species within the energetic orworking fluid discharged from the energy-conversion system. Similarsystems may be configured to control one or more intermediate productsor by-products in the reaction fluids of other reactive systems.

Expansion through an expansion stage of a work engine, such as a turbine58 or reciprocating engine, is relatively rapid and can be approximatedby a step drop in temperature or rapid temperature gradient, orpreferably as a rapid curvilinear temperature profile. Distributeddiluent mist delivery, mixing and evaporation, steam delivery or fluidacceleration may similarly provide relatively rapid temperaturereduction. Conductive heat transfer may be used for more gradualtemperature reduction. These methods may be combined to provide multiplecooling and equilibration methods.

FIG. 13 schematically shows the implications of various mixtures of air,a typical hydrocarbon fuel, and water/steam on a combustion process. Forillustrative purposes and in accordance with the state-of-the-artcatalytic emissions reduction, desired emissions levels for NOx and COare assumed to be at or below 1 ppmv. (Note the concentrations shown areat the nominal outlet concentration. To compare with other applications,these concentrations would need to be converted such as to a dry ppmvd15% O₂ basis or mg/GJ output or lb/MWhe output. A 1 ppmv NOx emissionnear 1.05 relative air/fuel ratio Lambda compares to about 3 ppmvconverted to a 15% O₂ basis.) The temperature of the ProgressiveCombustion region is schematically shown as correlating to the stabilityof the system, since higher temperatures maintain higher reactivities inthe combusting gas.

The diagram nominally identifies a reference water-to-fuel ratio, W₀,which corresponds to the water-to-fuel ratio preferable to give a flametemperature of approximately 1600° C. For different unburned mixtures,this value of W₀ varies, being generally higher as the temperature ofunburned fluid mixture is higher, and as the energy density of the fuelis higher. A W₀ coinciding with a flame temperature of 1600° C. isdepicted here as a reference state, 1600° C. being an approximately thehottest mean temperatures likely to be produced in the combustor ofconventional metal-based gas turbines. Hotter temperatures may be usedwith ceramics.

With continued reference to FIG. 13, the highest flame temperaturetypically coincides with lower quantities of diluent. In the system ofFIG. 13, this diluent may be in the form of water/steam, excess air, orexcess fuel. Consequently, the flame temperature isotherms increase intemperature as they approach the zero-water (W=0), stoichiometric(Lambda=1) condition.

NOx formation in combustion systems is generally promoted by highertemperatures (typically above about 1400° C.) and the presence of oxygenand nitrogen. Accordingly, in FIG. 13, the conditions for significantNOx formation is generally for lower diluent levels which support highertemperatures, while being generally skewed to lean conditions where moresubstantial quantities of molecular oxygen and nitrogen from excess airare present.

Generally speaking, greater than stoichiometric amounts of oxygensupport the oxidation of CO to CO₂ such that CO concentration mayapproach ppm levels. Consequently lean conditions (i.e. Lambda>1) arepreferable for reducing CO concentrations to or below ppm levels. Theequilibrium concentration of CO increases above 1 ppm as systemtemperatures increase above about 1200° C. to 1400° C. In FIG. 13, thisboundary is schematically shown as the upper-temperature boundary of theCO removal region. Since lower temperatures support lower equilibriumconcentrations of CO, the lower-temperature boundary of the CO removalregion is defined by condition wherein temperatures are too low tosupport high-enough kinetic rates to the lower CO equilibriumconcentration levels. With continued reference to FIG. 13, if more timeis allowed for equilibration at lower temperatures, thelower-temperature boundary of the CO removal region shifts to lowertemperatures. About a ten-fold increase in available residence timetypically results in about a 100° C. increase in the minimum temperaturetypically provided to reduce CO concentrations to about 2 ppm levels orless. Possible equilibration operating regimes to control COconcentrations are shown for possible residence times of 10 ms, 100 ms,and one second.

FIG. 13 shows that numerous fluid composition paths may be used tocontrol emissions to desired levels while satisfying stabilityconstraints. For example, a system configured only for high-stabilitymay have high NOx. The method of performing progressive combustionfollowed by equilibration is a suggested way of addressing thesemultiple demands. By passing the combusting/combusted fluids through asequence of conditions during a single combustion process, more than oneemission target may be met.

As an example, FIG. 13 shows two example sequences of methodsdemonstrating this strategy. In case A, slightly lean wet progressivecombustion may be followed by final water to achieve CO equilibrationconditions. (e.g., 1.0<Lambda<1.1) Here, Progressive Combustion mayfirst be performed at 1400° C., as shown at location “PC-A”. After allof the fuel and air, with some water, is added in this ProgressiveCombustion region, the resulting combusted gas is maintained at thiscondition for a first equilibration period. This preferably provides ahigh degree of removal of UHCs and “above-equilibrium” CO levels. Thisequilibration period is identified as “EQ1-A”.

While a temperature of about 1400° C. is below temperatures of high NOxproduction, it is outside the conditions desired to provide very low COlevels. Consequently, the hot fluid is preferably cooled with moreresidence time to reduce the CO. e.g., more water may be added,establishing a new gas temperature of about 1200° C. Providingsufficient residence time may bring the gas to a condition that reducesCO concentrations to below about 1 ppm, “EQ2”. According to theestablished criteria, the gas is best held at condition “EQ2” for a COreduction dwell time of about 10 ms or more. If the product gases are tobe employed at a lower temperature (for example in a turbine systemwhere the TIT less than about 1200° C.), more water might then be addedafter the second equilibration period “EQ2”. The gas may be expandedthrough a turbine.

FIG. 14 shows the results of a numerical simulation of an example ofthis strategy. Fluid delivery during progressive combustion is heremodeled as linear and distributed or as pseudo discrete using numerousorifices. During the period of progressive combustion, “PC-A”, thetemperature of the combusting mixture is maintained below about 1400° C.due to the continual presence of incompletely combusted fuel, maintainedby the constant delivery of uncombusted mixture. For similar reasons, COand UHC levels may have high concentrations. E.g., on the order of 100ppmv. After progressive combustion, further residence time is preferablyprovided for burnout and gas equilibration. e.g., Equilibration orburnout region “EQ1-A”, wherein rates of CO and UHC removal areinitially very high. UHC concentrations are preferably decreased throughseveral orders of magnitude within the burnout region. E.g., to sub-ppblevels. CO concentration also drops and approaches equilibrium after avery short time in the burnout region. E.g., it may equilibrate to about10 ppmv after about 1 ms.

In configurations such as depicted in FIG. 13, and FIG. 14, water and/orsteam diluent is preferably delivered into the hot fluid downstream ofprimary combustion using one or more of the technologies incorporated byreference. E.g., water or steam are preferably delivered through one ormore perforated tubes positioned transversely to the fluid flow. Thisdiluent delivery is preferably configured and/or controlled to providedesired transverse temperature profiles in the hot combustion fluidexiting the combustor. Alternatively orifices or nozzles in combustorwalls may be used as exemplified in the patents to Ginter.

With continued reference to FIG. 13, “PC-B” identifies a preferred casein which Progressive Combustion is allowed to occur under slightly richconditions (0.9<Lambda<1.0). This is preferably followed by anequilibration or burnout region “EQ2-B.” More oxidant and diluent arepreferably delivered to establish the second equilibration conditions“EQ2”. These are preferably delivered through nozzles or orifices aboutperforated tubes or walls as described by the technology incorporated byreference. The amount of oxidant delivered is preferably sufficient tochange the oxidant/fuel ratio by at least 2%. This preferably pushes thestoichiometry from the rich region with insufficient oxidant to combustall the fuel, to the region region with an excess of oxidant.

Simulation results of such a preferred rich to lean configuration areshown in FIG. 15. The low availability of oxygen under the richconditions results in less NOx being formed compared to progressivecombustion under slightly lean conditions. High concentrations of UHCare present in the first equilibration burnout region “EQ1”. Howeverthese are light molecules, typically methyl species, which are quicklyoxidized in the second equilibration region “EQ2”. This exemplary richto lean method results in about 20% to 40% less NOx than the case forprogressive combustion under slightly-lean conditions for the conditionschosen.

Many similar reaction paths incorporating such Progressive Combustionand Equilibration methods may be applied in different configurations asbest suits the goals of the designer.

Progressive Reactions and Equilibration

Various embodiments of the progressive combustion and equilibrationmethods described may be beneficially used to conduct a variety ofchemical and biochemical reactions, especially exothermic reactions.Configurations similar to the embodiments described above may be usedwith a reactant fluid comprising a reactant instead of fuel fluid.Similarly, a co-reactant fluid comprising a co-reactant may be usedinstead of the oxidant fluid. A diluent fluid comprising one or morecompounds suitable to dilute the exothermic reaction while notinterfering with the desired reaction or causing excessive byproducts ispreferably used. These may include hydrocarbons or other non-aqueouschemicals for non-aqueous reaction systems. The thermo-spatialequilibration methods including work extraction described toprogressively reduce CO emissions may similarly be used to progress theprimary reaction between reactants and reduce intermediate reactionproducts. The thermo-spatial methods used to constrain byproductformation, such as NOx, may similarly be used to constrain undesiredreaction byproducts.

Such methods preferably control the streamwise rate of diluted reactablefluid delivery to desirably constrain streamwise composition andtemperature within desirable ranges to maintain stable reaction rates,progress the reaction to reduce intermediate products, and constrainresidual byproducts. These thermo-spatial configuration and controlmethods improve product quality and value. They improve the rate atwhich reactants can be processed, and provide more compact components.The work extraction methods exemplified may be used to further recoverenergy and reduce processing costs.

The reactions are preferably conducted to reduce intermediate productsto a concentration less than or equal to 100 ppmv. The temperature ofthe hot fluid is preferably constrained to below 1700° C. at the exit ofone of the reaction regions or to similar temperatures. E.g., at theinlet to an expander. Temperatures within reaction regions may also bepreferably controlled to similar temperatures.

Hot fluid is preferably delivered to the inlet of the reactor toinitiate the reaction and bring it to a desired reaction temperatureaccording to the respective chemical process. E.g., the fluids may beheated to a temperature where the reaction is at least 200% greater thanthat with reacting fluids at ambient conditions.

For example, such progressive reactions and chemical equilibration mayinclude, but are not limited to: alkylations, carbonylations,carbamylations, chlorinations, direct oxidations, ethoxylations,halogenations, hydroformylations, hydrogenations, nitrations, solutionpolymerizations, sulfations, and sulfonations. Such diluted progressivereactions may be used to prepare a wide variety of chemicals,biochemicals and foods. These may include, but are not limited to: asurfactant, a demulsifying agent, an emulsifying agent, a hydrocarbonfuel, a synthetic lubricant, a halogenated hydrocarbon, a hydrocarbonsolvent, an organic polymer, a fire retardant, a fabric treatment agent,an antibiotic, an antiviral agent, an anti-pathogenic agent, afungicide, a herbicide, an insecticide, a pesticide, a rodenticide, afood product, and the like.

Various embodiments may be used to prepare the following chemicals:ethanol from ethylene, ethylene oxide by oxidation of ethylene, ethyleneamines from ethylene oxide, ethylene glycol by oxygenating ethylene,ethanol amines from ethylene dichloride, hydrogen peroxide usinganthraquinone, maleic anhydride, n-butanephenol from propylene andbenzene, adipic acid from phenol, caprolactam from cyclohexane,cyclohexanol from benzene, ethylene glycol ethyl ethers, chloroaceticacid from acetic acid, propylene oxide, n-Butanol from propylene,acrylic acid from propylene, tetrahydrofuran from maleic acid, andn-Butyl acrylate by esterfying acrylic acid. The emulsifying agents orsurfactants may include: alkyl benzene sulfonates, linear alkylbenezenesulfonates, secondary alkane sulfonates, ester sulfonates, alpha olefinsulfonates, alkyl glyceryl ether sulfonates, alkyl glyceryl sulfonates,methyl ester sulfonates, natural fat sulfonates, natural oil sulfonates,alcohol sulfates, alcohol ether sulfates and the like.

Other embodiments preferably utilize the methods described herein and inthe technology incorporated by reference to controllably mix fluids andconduct endothermic reactions. These may include delivering heateddiluents to add heat to the system, increase the reactants' temperatureand promote the reaction.

Generalization

From the foregoing description, it will be appreciated that a novelapproach for mixing, delivering and reacting three or more fluids tocontrolling emissions or components from intermediate or byproductreactions has been disclosed using one or more methods described herein.This method of controlling emissions may be applied to a broad range ofcombustion systems such as including gas-turbines, internal combustionengines, furnaces, burners, process heaters, incinerators, flares, andsubterranean combustors.

The flows and/or composition of the associated fuel, oxidant and diluentfluids may be varied to achieve a desired chemical composition orcomposition range of the working or energetic fluid, to control orreduce intermediate and/or byproduct emissions. The kinetic andthermodynamic principles herein applied to controlling UHC, CO & NOxemissions can, by extension, be applied to the control of other chemicalspecies present in the energetic or working fluid of a combustionsystem, chemical refining process, or other chemical reaction orprocessing system.

While the components, techniques and aspects of the invention have beendescribed with a certain degree of particularity, it is manifest thatmany changes may be made in the specific designs, constructions andmethodology herein above described without departing from the spirit andscope of this disclosure.

Where dimensions are given they are generally for illustrative purposeand are not prescriptive. Of course, as the skilled artisan willappreciate, other suitable sizes, orientations, configurations anddistributions of fluid delivery orifices, fluid passages, and othercomponents may be efficaciously utilized, as needed or desired, givingdue consideration to the goals of achieving one or more of the benefitsand advantages as taught or suggested herein.

Where combustor, mixing chambers and orifice delivery configurations areprovided, similar two or three dimensional configurations orcombinations of those configurations may be efficaciously utilized,including varying the nominal thicknesses, diameters, cross sectionalshapes, spacings, orientations, and other dimensions and parameters forthe combustor walls, mixing chambers and orifices. Additionalequilibration regions may be added or configured in the combustion orreaction system to control intermediate or byproduct species as desiredor needed. E.g., by controlling one or more of the carbon, oxygen,hydrogen, and nitrogen compositions. Where fluid delivery refers togases, it will be appreciated that the fluids may comprise liquid spraysor mists.

Where the terms fuel, reactant, diluent, water, carbon dioxide, air,oxygen, oxidant, and co-reactant have been used, the methods aregenerally applicable to other combinations of those fluids or to othercombinations of other reacting and diluent fluids. Concentrations ofother elements such as sulfur, phosphorus, halogens, noble gases, andselected metals or ceramics may also be controlled.

Where fluid quantities are referred to, these methods are generallyapplicable to include quantities delivered at multiple times, and tocontinuous fluid flows. Where assembly methods are described, variousalternative assembly methods may be efficaciously utilized to achieveconfigurations to achieve the benefits and advantages of one or more ofthe embodiments as taught or suggested herein.

Where transverse, axial, radial, circumferential or other directions arereferred to, it will be appreciated that any general coordinate systemusing curvilinear coordinates may be utilized including Cartesian,cylindrical, spherical or other specialized system such as an annularsystem. Similarly when one or more transverse or axial distributions orprofiles are referred to, it will be appreciated that the configurationsand methods similarly apply to spatial control in one or morecurvilinear directions as desired or prescribed.

While the components, techniques and aspects of the invention have beendescribed with a certain degree of particularity, it is manifest thatmany changes may be made in the specific designs, constructions andmethodology herein above described without departing from the spirit andscope of this disclosure.

Various modifications and applications of the invention may occur tothose who are skilled in the art, without departing from the true spiritor scope of the invention. It should be understood that the invention isnot limited to the embodiments set forth herein for purposes ofexemplification, but includes the full range of equivalency to whicheach element is entitled.

COMPONENT LIST

1 Combustor 2 Combustion Chamber 3 Primary Combustion Region 4 1stEquilibration Region or Burnout Region 5 2nd Equilibration/InterstageRegion 6 Premixing Region 7 Common Premixing Region 8 Premix-CombustionWalls 9 Premix-Premix Walls 10 1st Equilibration Fluid Control Device 112nd Equilibration Fluid Control Device 12 Perforated Pilot Fire Tube 131″ Fire Tube 14 2″ Fire Tube 15 3″ Fire Tube 16 4″ Fire Tube 17 PilotMixture Inlet 18 Stage 1 Mixture Inlet 19 Stage 2 Mixture Inlet 20 Stage3 Mixture Inlet 21 Plenum Cap 22 1″ Fire Tube Plate 23 2″ Fire TubePlate 24 3″ Fire Tube Plate 25 4″ Fire Tube Plate 26 Pilot Plenum 27Stage 1 Plenum 28 Stage 2 Plenum 29 Stage 3 Plenum 30 Pilot IgniterOrifices 31 Pilot Combustion region Orifices 32 Stage 1 Orifices 33Stage 2 Orifices - Set 1 34 Stage 2 Orifices - Set 2 35 Stage 2Orifices - Set 3 36 Stage 3 Orifice - Set 1 37 Stage 3 Orifice - Set 238 Stage 3 Orifice - Set 3 39 Pilot Combustion region 40 Stage 1Combustion region 41 Stage 2 Combustion region 42 Stage 2 - Set 1 MicroRegion 43 Stage 2 - Set 2 Micro Region 44 Stage 2 - Set 3 Micro Region45 Stage 3 Combustion region 46 Stage 3 - Set 1 Micro Region 47 Stage3 - Set 2 Micro Region 48 Stage 3 - Set 3 Micro Region 49 Igniter (GlowPlug) 50 Electric Power Source 51 Igniter Flange 52 Thermal Mass FlameHolder 53 Insulation 54 Turbine Power System 55 Electric Generator 56Thrust Bearings 57 Additional Bearings 58 Turbine1 59 Turbine2 60Turbine3 61 Shaft1 62 Shaft2 63 Compressor F1 Oxidant Inflow toCombustor F2 Fuel Inflow to Combustor F3 Diluent Inflow to Combustor F4Uncombusted Inflow to Combustor F5 Uncombusted Inflow to Pilot F6Uncompressed Oxidant/Air F7 Premix Fluids F8 Pilot Fluids F9 CombustorFluid Flow F10 Energized Combustible Fluids F11 1st EquilibrationDelivery Fluids F12 Combustor Product Fluids before 1st equilibrationF13 Combustor Product Fluids after 1st equilibration F14 CombustorProduct Fluids before 2nd equilibration F15 2nd Equilibration DeliveryFluids F16 Combustor Product Fluids after 2nd equilibration P17Combustor Product Fluids before 3rd equilibration F18 3rd EquilibrationDelivery Fluids F19 Combustor Product Fluids after 3rd equilibration F20Pilot to Stage 1 Flow F21 Stage 1 to Stage 2 Flow F22 Stage 2 to Stage 3Flow F23 Stage 3 to Burnout Flow F24 Burnout to Exhaust Flow F25 FullyExpanded Gases

1. A clean combustion system, comprising: a system inlet for hot fluid;a system outlet for hot combustion fluid in fluid communication with thesystem inlet; a plurality of combustion regions in streamwise fluidcommunication with each other and with the system inlet and outlet, andconfigured to combust fuel fluid comprising a fuel, oxidant fluidcomprising an oxidant, and diluent fluid comprising added water, wherebyforming a hot combustion fluid; each combustion region configured tosustain combustion within the region and comprising: at least one inletconfigured to deliver said fuel, oxidant and diluent fluids; an inletfor upstream fluid; and an outlet for hot combustion fluid; whereinthermal energy provided by the hot combustion fluid from an upstreamregion is necessary to sustain combustion in a downstream region; andthe volume concentration of residual CO in the fluid at the systemoutlet is less than 25 ppmvd at 15% O₂; and the volume concentration ofany NOx formed within the combustion regions is less than 25 ppmvd at15% O₂; and the temperature of the hot combustion fluid is less thanabout 1700° C. as it exits the system.
 2. The combustion system of claim1, wherein the diluent comprises at least one of liquid water and carbondioxide.
 3. The combustion system of claim 2, wherein one or both of thecarbon dioxide or water are recovered from the combustion gases exitingthe system.
 4. The combustion system of claim 1, wherein any one or moreof combustion, a hot surface, an electromagnetic energy source or apyrophoric fluid reaction, heats the fluid entering the system inlet. 5.The combustion system of claim 4, wherein the thermal energy provided bythe hot fluid entering the system inlet is necessary to sustaincombustion in a downstream combustion region.
 6. The combustion systemof claim 1, wherein one or both of fuel fluid and oxidant fluid, orpremixed fuel-oxidant-fluid are premixed with diluent fluid beforedelivery into one or more of said combustion regions.
 7. The combustionsystem of claim 1, wherein fuel, oxidant and diluent fluid are premixedbefore delivery into one or more of said combustion regions.
 8. Thecombustion system of claim 1, wherein fuel and oxidant fluid arepremixed without sustained combustion before delivery into any one ormore of said combustion regions.
 9. The combustion system of claim 1,wherein fuel, oxidant and diluent fluid are premixed without sustainedcombustion before delivery into any one or more of said combustionregions.
 10. The combustion system of claim 1, further comprising atleast one mixing region in streamwise fluid communication with thesystem inlet and outlet and with said combustion regions and comprising:one or more inlets configured to deliver one or both of diluent oroxidant fluid.
 11. The combustion system of claim 10, wherein the saidat least one mixing region is downstream of the combustion regions. 12.The combustion system of claim 1, wherein the mass delivery flow rate ofdiluent entering any one or more of said combustion regions is 150% ormore of the mass delivery flow rate of fuel fluid entering thecombustion region.
 13. The combustion system of claim 12, wherein themass delivery flow rate of diluent entering the combustion region is300% or more of the fuel fluid entering the combustion region.
 14. Thecombustion system of claim 1, wherein the volume concentration of NOxformed within the combustion regions is less than 5 ppmvd at 15% O₂. 15.The combustion system of claim 1, wherein the volume concentration ofresidual CO in the hot combustion fluid at the system outlet is lessthan 5 ppmvd at 15% O₂.
 16. The combustion system of claim 1, whereinthe temperature of the hot combustion fluid is less than about 1250° C.as it exits the system.
 17. The combustion system of claim 1, furthercomprising an expander, wherein the temperature of the hot combustionfluid entering the expander is greater than 1150° C.
 18. The combustionsystem of claim 1, wherein the temperature of the hot combustion fluidis greater than about 650° C. as it exits the system.
 19. The combustionsystem of claim 1, wherein the residence time of the combustion fluidfrom the system inlet to the system outlet is greater than 1millisecond.
 20. The combustion system of claim 19, wherein theresidence time of the combustion fluid from the system inlet to thesystem outlet is greater than 100 milliseconds.
 21. The combustionsystem of claim 19, wherein the residence time of the combustion fluidfrom the system inlet to the system outlet is greater than 1 second. 22.The combustion system of claim 1, wherein the hot combustion fluid isutilized to energize a work engine configured to generate electricity23. The combustion system of claim 22, wherein said electricityenergizes a user load configured to convert electricity to mechanicalpower, light, or to add or remove heat.
 24. The progressive combustionsystem of claim 23, further comprising a transmission system configuredto transmit electricity generated over a distance exceeding about 8 km(5 miles).
 25. A method of combustion of fluids in a system comprisingthe steps of: configuring a plurality of combustion regions instreamwise communication; providing fuel fluid comprising a fuel,oxidant fluid comprising an oxidant and diluent fluid comprising adiluent into each of the combustion regions through one or more inlets;sustainably combusting diluted fuel-oxidant fluid within each region;providing at least some of the hot fluid from an upstream region to adownstream combustion region characterized that the thermal energydelivered by said hot fluid is necessary to sustain combustion in thedownstream region; controlling the oxidant, fuel and diluent fluid flowsentering said regions to reduce the: volume concentration of residual COin the fluid at the system outlet to less than 25 ppmvd at 15% O₂; andone or both of the volume concentration of NOx formed within thecombustion regions to less than 25 ppmvd at 15% O₂; and the temperatureof the hot combustion fluid to less than about 1700° C. as it exits thesystem.
 26. The method of claim 25, wherein the step of sustainablycombusting the fluid within any one or more of said regions furthercomprises controlling the mass delivery flow rate of any one or more ofdiluent, oxidant or fuel fluid such that the mean temperature of the hotcombustion fluid is maintained above the critical temperature T_(crit)defining neutrally stable combustion.
 27. The method of claim 25,wherein the step of sustainably combusting the fluid within any one ormore of said regions further comprises controlling the mass deliveryflow rate of any one or more of diluent, oxidant or fuel fluid such thatthe mean temperature of the mixed combustion fluid within the region ismaintained above the ignition temperature Tign.
 28. The method of claim25, wherein the step of sustainably combusting the fluid within any oneor more of said regions further comprises controlling the delivery of atleast one of diluent, oxidant or fuel fluid such that the mass deliveryflow rate delivery ratio R of said fluid to hot combustion fluid is lessthan the critical delivery ratio R_(CRIT), whereby maintaininginherently stable combustion.
 29. The method of claim 25, wherein thefluid flow rate of at least one or more of oxidant, fuel or diluentfluid differs in any one or more of said combustion regions as comparedto the fluid flow rate of said fluids in any other said combustionregions.
 30. The method of claim 25, additionally comprisingpressurizing to greater than 500 kPa at their inlets any one or more ofthe hot fluid, and the fuel, oxidant and diluent fluids.
 31. The methodof claim 25, wherein the diluent comprises at least one of liquid waterand carbon dioxide.
 32. The method of claim 31, additionally comprisingrecovering one or both of the water and carbon dioxide from thecombustion gases exiting the system.
 33. The method of claim 25,additionally comprising heating the fluid entering the system inlet withany one or more of following methods: with combustion; contacting itwith a hot surface; heating it with an electromagnetic energy source; ora pyrophoric fluid reaction.
 34. The method of claim 33, wherein thethermal energy provided by the hot fluid entering the system inlet isnecessary to sustain combustion in a downstream combustion region. 35.The method of claim 25, additionally comprising premixing one or both offuel fluid and oxidant fluid, or premixed fuel-oxidant-fluid withdiluent-fluid before delivery into one or more of said combustionregions.
 36. The method of claim 25, additionally comprising premixingfuel, oxidant and diluent fluid before delivery into one or more of saidcombustion regions.
 37. The method of claim 25, additionally comprisingpremixing fuel and oxidant fluid without combustion before delivery intoany one or more of said combustion regions.
 38. The method of claim 25,additionally comprising premixing fuel, oxidant and diluent fluidwithout sustained combustion before delivery into any one or more ofsaid combustion regions.
 39. The method of claim 25, additionallycomprising configuring at least one mixing region in streamwise fluidcommunication with the system inlet and outlet and with said combustionregions and further comprising: configuring one or more inlets todeliver one or both of diluent and oxidant fluid.
 40. The method ofclaim 39, additionally comprising configuring said mixing regiondownstream of the plurality of combustion regions.
 41. The method ofclaim 25, additionally comprising flowing diluent and fuel fluid intoany one or more of said regions wherein the mass delivery flow ratio ofdiluent to fuel is 150% or more.
 42. The method of claim 41, wherein themass delivery flow ratio of diluent to fuel fluid is 300% or more. 43.The method of claim 25, additionally comprising controlling the volumeconcentration of NOx formed within the combustion regions to less than 5ppmvd at 15% O₂.
 44. The method of claim 25, additionally comprisingcontrolling the volume concentration of residual CO in the fluid at thesystem outlet to less than 5 ppmvd at 15% O₂.
 45. The method of claim25, additionally comprising controlling the temperature of the hotcombustion fluid to less than about 1250° C. as it exits the system. 46.The method of claim 25, additionally comprising configuring an expanderin streamwise communication with the system inlet and outlet and saidcombustion regions, wherein the temperature of the hot combustion fluidentering the expander is greater than 950° C.
 47. The method of claim25, additionally comprising controlling the temperature of the hotcombustion fluid to greater than about 650° C. as it exits the system.48. The method of claim 25, additionally comprising controlling theresidence time of the hot combustion fluid from the system inlet to thesystem outlet to greater than 1 millisecond.
 49. The method of claim 48,additionally comprising controlling the residence time of the hotcombustion fluid from the system inlet to the system outlet to greaterthan 100 milliseconds.
 50. The method of claim 48, additionallycomprising controlling the residence time of the combustion fluid fromthe system inlet to the system outlet to greater than 1 second.
 51. Themethod of claim 25, additionally comprising utilizing the hot combustionfluid to energize a work engine configured to generate electricity. 52.The method of claim 51, wherein said electricity energizes a user loadconfigured to convert electricity to mechanical power, light, or to addor remove heat.
 53. The method of claim 52, further comprisingtransmitting said generated electricity over a transmission system overa distance exceeding about 8 km (5 miles).
 54. A clean equilibratingcombustion system comprising: a primary combustion system configured toform hot combustion fluid comprising products of fuel combustion,residual oxidant fluid, intermediate combustion products comprising CO,and optionally comprising NOx; an equilibration system inlet configuredto receive hot combustion fluid from the primary combustion system; anequilibration system outlet for equilibrated combustion fluid instreamwise fluid communication with the system inlet; at least oneequilibration region with an inlet and an outlet for hot combustionfluid in streamwise fluid communication with the system inlet and outletand configured to reduce the volume concentration of CO and to constrainthe volume concentration of NOx; wherein: the temperature of the hotcombustion fluid is reduced by at least 5° C. as it transits saidequilibration region; the residence time of hot combustion fluid passingthrough said region is greater than 0.7 ms; the volume concentration ofresidual CO in the fluid at the system outlet is less than 25 ppmvd at15% O₂; and the volume concentration of NOx formed within the primarycombustion system and the equilibration system is less than 25 ppmvd at15% O₂; and the temperature of the hot combustion fluid is less thanabout 1550° C. as it exits the system.
 55. The combustion system ofclaim 54, further comprising at least a first turbine expander region instreamwise fluid communication with the equilibration system inlet andupstream of at least one equilibration region, and at least a secondturbine expander region downstream of said equilibration region and influid communication with the system outlet.
 56. The combustion system ofclaim 55, further comprising a second equilibration region upstream ofthe system outlet and downstream of the second expander region and influid communication with them.
 57. The combustion system of claim 54,additionally comprising an inlet configured to deliver diluent fluidcomprising added water.
 58. The combustion system of claim 57, whereinsaid diluent fluid comprises at least one of liquid water and carbondioxide.
 59. The combustion system of claim 58, wherein one or both ofthe carbon dioxide and water are recovered from the combustion gasesexiting the system.
 60. The combustion system of claim 57, wherein theresidence time of hot combustion fluid in the system with added water isat least 50% longer than the residence time of the hot combustion fluidin the system without added water.
 61. The combustion system of claim57, wherein the equilibration region is configured to reduce thetemperature of the hot combustion fluid exiting the system by at least50° C. or more lower with added water than the configuration of theequilibration region to reduce the temperature without added water. 62.The combustion system of claim 54, additionally comprising an inletconfigured to deliver diluent fluid comprising added water to at leastone equilibration region.
 63. The combustion system of claim 62, whereinthe mass delivery flow rate of water added to said equilibration regionis greater than 1% of the hot combustion fluid flow.
 64. The combustionsystem of claim 63, wherein the mass delivery flow rate of water addedto said equilibration region is greater than 5% of the hot combustionfluid flow.
 65. The combustion system of claim 54, wherein the increasein volume concentration of NOx within the equilibration system is lessthan 5 ppmvd at 15% O₂.
 66. The combustion system of claim 54, whereinthe volume concentration of CO exiting the equilibration system is lessthan the CO concentration entering the equilibration system.
 67. Thecombustion system of claim 54, wherein the residual volume concentrationof CO exiting the equilibration system is less than 5 ppmvd at 15% O₂.68. The combustion system of claim 54, wherein the temperature of thehot combustion fluid is less than about 1300° C. as it exits the system.69. The combustion system of claim 54, wherein the temperature of thehot combustion fluid is greater than about 800° C. as it exits thesystem.
 70. The combustion system of claim 54, wherein saidequilibration region additionally comprises an expander in streamwisefluid communication with the equilibration system inlet and outletwherein the temperature of the hot combustion fluid is reduced by atleast 50° C. as it transits the expander.
 71. The combustion system ofclaim 54, wherein the cross-sectional area of at least one equilibrationregion is reduced by at least 50% between the inlet and the outlet forhot combustion fluid in the region.
 72. The combustion system of claim54, wherein said equilibration region additionally comprises an inletconfigured to deliver oxidant fluid.
 73. The combustion system of claim54, wherein a majority of said temperature reduction occurs in theupstream 50% of the streamwise fluid path length of said region.
 74. Thecombustion system of claim 54, wherein work is extracted from theequilibration system in order to reduce the temperature of the hotfluid.
 75. The combustion system of claim 54, wherein the residence timeof hot combustion fluid in the system is greater than 10 ms.
 76. Thecombustion system of claim 75, wherein the residence time of hotcombustion fluid in the system is greater than 100 ms.
 77. Thecombustion system of claim 54, wherein the ratio of residual oxidant toproducts of fuel combustion, as they exit the system, is between 0.01and 1.00 times the stoichiometric ratio of fuel delivered to the primarycombustion system.
 78. The combustion system of claim 54, wherein thehot combustion fluid transiting the equilibration system is utilized toenergize a work engine configured to generate electricity
 79. Thecombustion system of claim 78, wherein said electricity energizes a userload configured to convert electricity to at least one of mechanicalpower, light, adding heat, or removing heat.
 80. The combustion systemof claim 79, further comprising a transmission system configured totransmit electricity generated over a distance exceeding about 8 km (5miles).
 81. The combustion system of claim 54, wherein at least 75% ofsaid temperature reduction occurs in less than 50% of the streamwisefluid path length of said equilibration region.
 82. The combustionsystem of claim 54, wherein said temperature reduction is greater than100° C.
 83. The combustion system of claim 54, additionally comprising aheat exchanger wherein at least 10% of said temperature reduction isderived from thermal energy exchanged with said heat exchanger.
 84. Theequilibration system of claim 83, wherein diluent fluid is heated withinsaid heat exchanger and wherein said diluent fluid is delivered intosaid primary combustion system.
 85. A method to reduce pollutantcomponents within a hot combustion fluid comprising fuel and oxidantfluids, the method comprising the steps of: generating hot combustionfluid within a primary combustion region; flowing hot combustion fluidfrom the primary combustion region through at least one equilibratingregion; providing a residence time within the equilibration region ofgreater than 0.5 ms; reducing the temperature of the hot combustionfluid by at least 5° C. as it transits said region; reducing the volumeconcentration of residual CO in the fluid at the system outlet to lessthan 25 pmvd at 15% O₂; constraining the volume concentration of NOxformed within the primary combustion system and the equilibration systemto less than 25 ppmvd at 15% O₂ at the system outlet; and constrainingthe temperature of the hot combustion fluid to less than about 1550° C.at the system outlet.
 86. The method of claim 85, wherein the methodadditionally comprises the steps of: expanding hot combustion fluidthrough at least one expansion stage downstream of and in streamwisefluid communication with the primary combustion region, wherein reducingthe fluid temperature; and providing a residence time for the expandedcombustion fluid in at least one equilibrating region downstream of theexpansion stage, wherein the equilibrating residence time is at least50% of the residence time of hot combustion fluid through the at leastone expansion stage.
 87. The method of claim 86, wherein the residencetime of hot combustion fluid in the equilibration region, including anytime to redirect the flow, is at least 175% of the residence time of hotcombustion fluid in the expansion stage.
 88. The method of claim 85,wherein the method additionally comprises: expanding the hot combustionfluid through a first expansion stage; flowing it through a firstequilibration region downstream of the first expansion stage; expandingthe hot combustion fluid through a second expansion stage downstream ofthe first equilibration region; flowing the fluid through a secondequilibration region downstream of the second expansion stage; themethod further comprising: expanding said hot combustion fluid along afirst curvilinear temperature path within said first expansion stagefollowed by equilibrating the hot fluid within said first equilibrationregion for a first residence time; and expanding said hot combustionfluid along a second curvilinear temperature path within said secondexpansion stage followed by equilibrating the hot fluid within saidsecond equilibration region for a second residence time.
 89. The methodof claim 88, wherein said second residence time is greater than saidfirst residence time.
 90. The method of claim 88, wherein the residencetime of hot combustion fluid in the first and second equilibrationregions is at least 150% of the residence time of hot combustion fluidin said respective first and second expansion regions.
 91. The method ofclaim 85, additionally comprising flowing diluent fluid comprising addedwater through an inlet to said equilibration region.
 92. The method ofclaim 91, wherein the diluent fluid comprises one of liquid water andcarbon dioxide.
 93. The method of claim 92, additionally comprisingrecovering one or both of said carbon dioxide or water from thecombustion gases exiting the system.
 94. The method of claim 91, whereinthe residence time of hot combustion fluid in the system is at least 50%longer with added water than the residence time of the hot combustionfluid in the system without added water.
 95. The method of claim 91,wherein the temperature of the hot combustion fluid exiting the systemis 50° C. or more lower than the temperature of hot combustion fluidexiting the system without added water.
 96. The method of claim 91,wherein the mass delivery flow rate of water added to said equilibrationsystem is greater than 1% of the hot combustion fluid flow.
 97. Themethod of claim 96, wherein the mass delivery flow rate of water addedto said equilibration system is greater than 5% of the hot combustionfluid flow.
 98. The method of claim 85, wherein the increase in volumeconcentration of NOx within the equilibration system is less than 3ppmvd at 15% O₂.
 99. The method of claim 85, wherein the increase involume concentration of CO entering the equilibration system is greaterthan the CO concentration exiting the equilibration system.
 100. Themethod of claim 85, wherein the residual volume concentration of COexiting the equilibration system is less than 5 ppmvd at 15% O₂. 101.The method of claim 85, wherein the volume concentration of NOx formedwithin the primary combustion system and the equilibration system isless than 2.7 ppmvd at 15% O₂ in a combustion system, or 0.032 kg/MWh ina power system.
 102. The method of claim 85, wherein the temperature ofthe hot combustion fluid is less than about 1300° C. and greater thanabout 800° C. as it exits the system.
 103. The method of claim 85,additionally comprising flowing oxidant fluid into said equilibrationregion through an inlet.
 104. The method of claim 85, wherein a majorityof said temperature reduction in the equilibration region occurs in theupstream 50% of the streamwise fluid path length of said region. 105.The method of claim 85, additionally comprising flowing fuel fluid andoxidant fluid into said primary combustion region wherein the ratio ofoxidant to fuel fluid is between 1.01 and 2.00 times the stoichiometricratio.
 106. The method of claim 85, additionally comprising flowing saidhot combustion fluid through a work engine configured to generateelectricity.
 107. The method of claim 106, further comprising utilizingsaid electricity to energize a user load configured to convertelectricity to mechanical power, light, or to add or remove heat. 108.The method of claim 85, wherein at least 75% of said temperaturereduction occurs in less than 50% of the streamwise fluid path length ofsaid equilibration region.
 109. The method of claim 85, wherein saidtemperature reduction is greater than 100° C.
 110. The method of claim85, additionally comprising exchanging heat with a heat exchangerwherein at least 10% of said temperature reduction is derived fromthermal energy exchanged with said heat exchanger.
 111. The method ofclaim 110, additionally comprising heating diluent fluid with some ofthe heat derived from the heat exchanger and delivering said heatdiluent fluid to the primary combustion system through a diluent fluidinlet.
 112. The method of claim 85, wherein the step of reducing thefluid temperature comprises reducing the temperature along a firstcurvilinear path and then along a second curvilinear path.
 113. Themethod of claim 112, wherein at least a portion of the step of providinga fluid residence time occurs after reducing the fluid temperature alonga first curvilinear path and before reducing the fluid temperature alongthe second curvilinear path.
 114. The system of claim 1, wherein thecombustion system is configured to combust the fuel with less oxidationthat is required to fully oxidize the fuel.
 115. The method of claim 25,wherein the step of sustainably combusting the fuel, further comprisescombusting fuel with less oxidant than is required to fully oxidize thefuel.
 116. A method of combusting oxidant, fuel and diluent fluidscomprising the steps of: flowing uncombusted oxidant, fuel and diluentfluids into a plurality of combustion regions in a streamwise sequencewith one or more mass delivery flow ratios of uncombusted fluids to hotcombustion fluid, whereby forming a mixed hot combustion fluid, whereinthe mass flow delivery ratios are between 0.33 and 1.50 times thecritical delivery flow ratio R_(crit) for each of said regions;controlling the mean temperature of the mixed hot combustion fluid ineach of said regions above its ignition temperature and below itsadiabatic combustion temperature; controlling at least one of thecomposition or the temperature of the fluids delivered to the regions tomaintain the adiabatic combustion temperature of the hot combustionfluid exiting the most downstream of said regions to be less than 1700°C.; characterized that the volume concentration of NOx produced by themethod is less than 25 ppmvd at 15% O₂.
 117. The method of claim 116,wherein the temperature in said plurality of combustion regions ismaintained to within 33% and 67% of the temperature range between theadiabatic and the ignition temperature of said fluid as it exits saidplurality of combustion regions.
 118. The method of claim 116, whereinsaid mass delivery flow rate delivery ratio is maintained to within 0.6and 1.3 times the critical delivery flow ratio.
 119. The method of claim116, wherein said diluent fluid comprises one or more of added water orcarbon dioxide.
 120. The method of claim 116, additionally comprisingthe steps of: maintaining said mass delivery flow ratio to be less thanthe critical delivery flow ratio in said plurality of regions; andmaintaining the temperature of the hot combustion fluid in saidplurality of regions to be greater than or equal to the criticaltemperature.
 121. The method of claim 116, wherein the step ofcontrolling the temperature, further includes controlling a temperaturein a region within a range including at least some time below thecritical temperature by controlling the mass delivery flow ratio withina range including at least some time above the critical delivery flowratio.
 122. The method of claim 116, additionally comprising the stepsof: increasing the temperature of the hot combustion fluid in at leastone of said plurality of regions by decreasing said mass delivery flowratio into said at least one region to a level lower than the criticaldelivery flow ratio, when the temperature of the hot fluid entering theregion is less than the critical temperature.
 123. The method of claim116, additionally comprising the steps of: decreasing the temperature ofthe hot combustion fluid in at least one of said plurality of regions byincreasing said mass delivery flow ratio into said at least one regionto a level higher than the critical flow ratio, when the temperature ofthe hot fluid entering the region is greater than the criticaltemperature.
 124. The method of claim 116, additionally comprisingflowing diluent and fuel fluid into any one or more said regions whereinthe mass delivery flow ratio of diluent to fuel of 150% or more. 125.The method of claim 124, additionally comprising flowing diluent andfuel fluid into any one or more of said regions with a mass deliveryflow ratio of diluent to fuel fluid wherein the mass delivery flow rateof diluent fluid is at least 300% of the fuel fluid mass delivery flowrate.
 126. The method of claim 116, wherein the step of addinguncombusted fluids to said plurality of regions additionally comprisescontrolling the delivery of uncombusted fluid into the plurality ofregions such that a progressive streamwise integrated delivery flowratio of said fluid is less than or equal to the progressive integratedcritical delivery flow ratio for the corresponding fluid compositions.127. The method of claim 116, additionally comprising controlling theadiabatic temperature in the plurality of regions by controlling thediluent mass delivery flow rate relative to the combustion heat releasedwithin the plurality of regions.
 128. The method of claim 116, whereinthe step of delivering fluids to the combustion regions additionallycomprises changing the oxidant to fuel ratio of the mixed combustionfluid by greater than 2% between any two of said plurality of regions.129. The method of claim 116, wherein the step of delivering fluids tothe combustion regions additionally comprises changing the oxidant tofuel ratio in the mixed combustion fluid from an excess of fuel in anupstream region to an excess of oxygen in a downstream region.
 130. Themethod of claim 119 wherein the step of delivering fluids comprisescontrolling the transverse temperature profile of the hot combustion gasby configuring and controlling the spatial delivery of diluent into thehot combustor gas.
 131. A method of cleanly reacting fluids comprisingthe steps of: configuring a plurality of reaction regions in streamwisecommunication; providing reactant fluid, co-reactant fluid and diluentfluid into each of the reaction regions through one or more inlets;sustainably reacting the reactant and the co-reactant in the presence ofdiluent within each region; providing at least some of the hot fluidfrom an upstream region to a downstream combustion region characterizedthat the thermal energy delivered by said hot fluid is necessary tosustain reaction in the downstream region; wherein controlling thereactant, co-reactant and diluent fluid flows entering said reactionregions to: reduce the volume concentration of residual intermediatereactant product in the system outlet fluid to less than 100 ppmv; andto constrain one or both of: the volume concentration of a primarydiluent reaction byproduct to less than 100 ppmv; and the temperature ofthe hot reactor system outlet to less than about 1700° C.